From 32f8c918ce1196c718fc1f3caad767df43ef8a5e Mon Sep 17 00:00:00 2001
From: methr0 <s6tameth@uni-bonn.de>
Date: Fri, 26 May 2023 09:46:09 +0200
Subject: [PATCH 01/29] add Discretizer file

---
 .../tabular/transformation/_discretizer.py    | 200 ++++++++++++++++++
 1 file changed, 200 insertions(+)
 create mode 100644 src/safeds/data/tabular/transformation/_discretizer.py

diff --git a/src/safeds/data/tabular/transformation/_discretizer.py b/src/safeds/data/tabular/transformation/_discretizer.py
new file mode 100644
index 000000000..f4fdbb5cd
--- /dev/null
+++ b/src/safeds/data/tabular/transformation/_discretizer.py
@@ -0,0 +1,200 @@
+from __future__ import annotations
+
+import warnings
+
+from sklearn.preprocessing import KBinsDiscretizer as sk_KBinsDiscretizer
+
+from safeds.data.tabular.containers import Table
+from safeds.data.tabular.transformation._table_transformer import TableTransformer
+from safeds.exceptions import TransformerNotFittedError, UnknownColumnNameError
+
+
+class Discretizer(TableTransformer):
+    """
+    The Discretizer transforms replaces a continuous variable by a variable that only has a finite amount of values.
+
+    Parameters
+    ----------
+    number_of_bins: float
+        The number of bins to be created.
+
+    Raises
+    ------
+    ValueError
+        If the given number_of_bins is less than 2.
+    """
+
+    def __init__(self, number_of_bins: float = 5):
+        self._column_names: list[str] | None = None
+        self._wrapped_transformer: sk_KBinsDiscretizer | None = None
+
+        if number_of_bins < 2:
+            raise ValueError("Parameter 'number_of_bins' must be >= 2.")
+        self.number_of_bins = number_of_bins
+
+    def fit(self, table: Table, column_names: list[str] | None) -> Discretizer:
+        """
+        Learn a transformation for a set of columns in a table.
+
+        This transformer is not modified.
+
+        Parameters
+        ----------
+        table : Table
+            The table used to fit the transformer.
+        column_names : Optional[list[str]]
+            The list of columns from the table used to fit the transformer. If `None`, all columns are used.
+
+        Returns
+        -------
+        fitted_transformer : TableTransformer
+            The fitted transformer.
+        """
+        if column_names is None:
+            column_names = table.column_names
+        else:
+            missing_columns = set(column_names) - set(table.column_names)
+            if len(missing_columns) > 0:
+                raise UnknownColumnNameError(list(missing_columns))
+
+        wrapped_transformer = sk_KBinsDiscretizer(n_bins=self.number_of_bins)
+        wrapped_transformer.fit(table._data[column_names])
+
+        result = Discretizer()
+        result._wrapped_transformer = wrapped_transformer
+        result._column_names = column_names
+
+        return result
+
+    def transform(self, table: Table) -> Table:
+        """
+        Apply the learned transformation to a table.
+
+        The table is not modified.
+
+        Parameters
+        ----------
+        table : Table
+            The table to which the learned transformation is applied.
+
+        Returns
+        -------
+        transformed_table : Table
+            The transformed table.
+
+        Raises
+        ------
+        TransformerNotFittedError
+            If the transformer has not been fitted yet.
+        """
+        # Transformer has not been fitted yet
+        if self._wrapped_transformer is None or self._column_names is None:
+            raise TransformerNotFittedError
+
+        # Input table does not contain all columns used to fit the transformer
+        missing_columns = set(self._column_names) - set(table.column_names)
+        if len(missing_columns) > 0:
+            raise UnknownColumnNameError(list(missing_columns))
+
+        data = table._data.copy()
+        data.columns = table.column_names
+        data[self._column_names] = self._wrapped_transformer.transform(data[self._column_names])
+        return Table._from_pandas_dataframe(data)
+
+    def inverse_transform(self, transformed_table: Table) -> Table:
+        """
+        Undo the learned transformation.
+
+        The table is not modified.
+
+        Parameters
+        ----------
+        transformed_table : Table
+            The table to be transformed back to the original version.
+
+        Returns
+        -------
+        table : Table
+            The original table.
+
+        Raises
+        ------
+        TransformerNotFittedError
+            If the transformer has not been fitted yet.
+        """
+        # Transformer has not been fitted yet
+        if self._wrapped_transformer is None or self._column_names is None:
+            raise TransformerNotFittedError
+
+        data = transformed_table._data.copy()
+        data.columns = transformed_table.column_names
+        data[self._column_names] = self._wrapped_transformer.inverse_transform(data[self._column_names])
+        return Table._from_pandas_dataframe(data)
+
+    def is_fitted(self) -> bool:
+        """
+        Check if the transformer is fitted.
+
+        Returns
+        -------
+        is_fitted : bool
+            Whether the transformer is fitted.
+        """
+        return self._wrapped_transformer is not None
+
+    def get_names_of_added_columns(self) -> list[str]:
+        """
+        Get the names of all new columns that have been added by the Discretizer.
+
+        Returns
+        -------
+        added_columns : list[str]
+            A list of names of the added columns, ordered as they will appear in the table.
+
+        Raises
+        ------
+        TransformerNotFittedError
+            If the transformer has not been fitted yet.
+        """
+        warnings.warn("Discretizer only changes data within columns, but does not add any columns.", stacklevel=1)
+        if not self.is_fitted():
+            raise TransformerNotFittedError
+        return []
+
+    # (Must implement abstract method, cannot instantiate class otherwise.)
+    def get_names_of_changed_columns(self) -> list[str]:
+        """
+         Get the names of all columns that may have been changed by the Discretizer.
+
+        Returns
+        -------
+        changed_columns : list[str]
+             The list of (potentially) changed column names, as passed to fit.
+
+        Raises
+        ------
+        TransformerNotFittedError
+            If the transformer has not been fitted yet.
+        """
+        if self._column_names is None:
+            raise TransformerNotFittedError
+        return self._column_names
+
+    def get_names_of_removed_columns(self) -> list[str]:
+        """
+        Get the names of all columns that have been removed by the Discretizer.
+
+        Returns
+        -------
+        removed_columns : list[str]
+            A list of names of the removed columns, ordered as they appear in the table the Discretizer was fitted on.
+
+        Raises
+        ------
+        TransformerNotFittedError
+            If the transformer has not been fitted yet.
+        """
+        warnings.warn("Discretizer only changes data within columns, but does not remove any columns.", stacklevel=1)
+        if not self.is_fitted():
+            raise TransformerNotFittedError
+        return []

From b2705e5bf666eaed8920929261e049aa053ab7e8 Mon Sep 17 00:00:00 2001
From: methr0 <s6tameth@uni-bonn.de>
Date: Fri, 26 May 2023 13:06:09 +0200
Subject: [PATCH 02/29] add tests for Discretizer

---
 .../tabular/transformation/_discretizer.py    |   3 +-
 .../transformation/test_discretizer.py        | 290 ++++++++++++++++++
 2 files changed, 292 insertions(+), 1 deletion(-)
 create mode 100644 tests/safeds/data/tabular/transformation/test_discretizer.py

diff --git a/src/safeds/data/tabular/transformation/_discretizer.py b/src/safeds/data/tabular/transformation/_discretizer.py
index f4fdbb5cd..cf2a37119 100644
--- a/src/safeds/data/tabular/transformation/_discretizer.py
+++ b/src/safeds/data/tabular/transformation/_discretizer.py
@@ -103,8 +103,9 @@ def transform(self, table: Table) -> Table:
 
     def inverse_transform(self, transformed_table: Table) -> Table:
         """
-        Undo the learned transformation.
+        Transform discretized data back to original feature space.
 
+        Note that this function does not regenerate the original data due to discretization rounding.
         The table is not modified.
 
         Parameters
diff --git a/tests/safeds/data/tabular/transformation/test_discretizer.py b/tests/safeds/data/tabular/transformation/test_discretizer.py
new file mode 100644
index 000000000..40600ce6c
--- /dev/null
+++ b/tests/safeds/data/tabular/transformation/test_discretizer.py
@@ -0,0 +1,290 @@
+import pytest
+from safeds.data.tabular.containers import Table
+from safeds.data.tabular.transformation._discretizer import Discretizer
+from safeds.exceptions import TransformerNotFittedError, UnknownColumnNameError
+
+
+class TestInit:
+    def test_should_raise_value_error(self) -> None:
+        with pytest.raises(ValueError, match="Parameter 'number_of_bins' must be >= 2."):
+            _ = Discretizer(1)
+
+
+class TestFit:
+    def test_should_raise_if_column_not_found(self) -> None:
+        table = Table(
+            {
+                "col1": [0.0, 5.0, 10.0],
+            },
+        )
+
+        with pytest.raises(UnknownColumnNameError):
+            Discretizer().fit(table, ["col2"])
+
+    def test_should_not_change_original_transformer(self) -> None:
+        table = Table(
+            {
+                "col1": [0.0, 5.0, 10.0],
+            },
+        )
+
+        transformer = Discretizer()
+        transformer.fit(table, None)
+
+        assert transformer._wrapped_transformer is None
+        assert transformer._column_names is None
+
+
+class TestTransform:
+    def test_should_raise_if_column_not_found(self) -> None:
+        table_to_fit = Table(
+            {
+                "col1": [0.0, 5.0, 10.0],
+            },
+        )
+
+        transformer = Discretizer().fit(table_to_fit, None)
+
+        table_to_transform = Table(
+            {
+                "col2": ["a", "b", "c"],
+            },
+        )
+
+        with pytest.raises(UnknownColumnNameError):
+            transformer.transform(table_to_transform)
+
+    def test_should_raise_if_not_fitted(self) -> None:
+        table = Table(
+            {
+                "col1": [0.0, 5.0, 10.0],
+            },
+        )
+
+        transformer = Discretizer()
+
+        with pytest.raises(TransformerNotFittedError):
+            transformer.transform(table)
+
+
+class TestIsFitted:
+    def test_should_return_false_before_fitting(self) -> None:
+        transformer = Discretizer()
+        assert not transformer.is_fitted()
+
+    def test_should_return_true_after_fitting(self) -> None:
+        table = Table(
+            {
+                "col1": [0.0, 5.0, 10.0],
+            },
+        )
+
+        transformer = Discretizer()
+        fitted_transformer = transformer.fit(table, None)
+        assert fitted_transformer.is_fitted()
+
+
+class TestFitAndTransform:
+    # the return value has a formate with "(0,int)\t1.0" and I don't understand how that happens and how the test should look like...
+    @pytest.mark.parametrize(
+        ("table", "column_names", "expected"),
+        [
+            (
+                Table(
+                    {
+                        "col1": [0.0, 5.0, 5.0, 10.0],
+                    },
+                ),
+                None,
+                Table(
+                    {
+                        "col1": [0.0, 5.0, 5.0, 10.0],
+                    },
+                ),
+            ),
+            (
+                Table(
+                    {
+                        "col1": [0.0, 5.0, 5.0, 10.0],
+                        "col2": [0.0, 5.0, 5.0, 10.0],
+                    },
+                ),
+                ["col1"],
+                Table(
+                    {
+                        "col1": ["(0, 0)\t1.0", "(0, 2)\t1.0","(0, 2)\t1.0", "(0, 3)\t1.0"],
+                        "col2": [0.0, 5.0, 5.0, 10.0],
+                    },
+                ),
+            ),
+        ],
+        ids=["None", "col1"]
+    )
+    def test_should_return_transformed_table(
+        self,
+        table: Table,
+        column_names: list[str] | None,
+        expected: Table,
+    ) -> None:
+
+        assert Discretizer().fit_and_transform(table, column_names) == expected
+
+    @pytest.mark.parametrize(
+        ("table", "number_of_bins", "expected"),
+        [
+            (
+                Table(
+                    {
+                        "col1": [0.0, 5.0, 5.0, 10.0],
+                    },
+                ),
+                2,
+                Table(
+                    {
+                        "col1": [0, 1.0, 1.0, 1.0],
+                    },
+                ),
+            ),
+            (
+                Table(
+                    {
+                        "col1": [0.0, 5.0, 5.0, 10.0],
+                    },
+                ),
+                10,
+                Table(
+                    {
+                        "col1": [0.0, 4.0, 4.0, 7.0],
+                    },
+                ),
+            ),
+        ],
+        ids=["2", "10"]
+    )
+    def test_should_return_transformed_table_with_correct_number_of_bins(
+        self,
+        table: Table,
+        number_of_bins: int,
+        expected: Table,
+    ) -> None:
+        print(Discretizer(number_of_bins).fit_and_transform(table, ["col1"]))
+        assert Discretizer(number_of_bins).fit_and_transform(table, ["col1"]) == expected
+
+    def test_should_not_change_original_table(self) -> None:
+        table = Table(
+            {
+                "col1": [0.0, 5.0, 10.0],
+            },
+        )
+
+        Discretizer().fit_and_transform(table)
+
+        expected = Table(
+            {
+                "col1": [0.0, 5.0, 10.0],
+            },
+        )
+
+        assert table == expected
+
+    def test_get_names_of_added_columns(self) -> None:
+        transformer = Discretizer()
+        with pytest.warns(
+            UserWarning,
+            match="Discretizer only changes data within columns, but does not add any columns.",
+        ), pytest.raises(TransformerNotFittedError):
+            transformer.get_names_of_added_columns()
+
+        table = Table(
+            {
+                "a": [0.0],
+            },
+        )
+        transformer = transformer.fit(table, None)
+        with pytest.warns(
+            UserWarning,
+            match="Discretizer only changes data within columns, but does not add any columns.",
+        ):
+            assert transformer.get_names_of_added_columns() == []
+
+    def test_get_names_of_changed_columns(self) -> None:
+        transformer = Discretizer()
+        with pytest.raises(TransformerNotFittedError):
+            transformer.get_names_of_changed_columns()
+        table = Table(
+            {
+                "a": [0.0],
+            },
+        )
+        transformer = transformer.fit(table, None)
+        assert transformer.get_names_of_changed_columns() == ["a"]
+
+    def test_get_names_of_removed_columns(self) -> None:
+        transformer = Discretizer()
+        with pytest.warns(
+            UserWarning,
+            match="Discretizer only changes data within columns, but does not remove any columns.",
+        ), pytest.raises(TransformerNotFittedError):
+            transformer.get_names_of_removed_columns()
+
+        table = Table(
+            {
+                "a": [0.0],
+            },
+        )
+        transformer = transformer.fit(table, None)
+        with pytest.warns(
+            UserWarning,
+            match="Discretizer only changes data within columns, but does not remove any columns.",
+        ):
+            assert transformer.get_names_of_removed_columns() == []
+
+
+class TestInverseTransform:
+    # inverse_transform doesn't regenerate the old table, it just transforms the discretized data back to original feature space
+    # need to test if the features are the same
+    @pytest.mark.parametrize(
+        "table",
+        [
+            Table(
+                {
+                    "col1": [0.0, 5.0, 5.0, 10.0],
+                },
+            ),
+        ],
+    )
+    def test_should_return_original_table(self, table: Table) -> None:
+        transformer = Discretizer().fit(table, None)
+
+        assert transformer.inverse_transform(transformer.transform(table)) == table
+
+    def test_should_not_change_transformed_table(self) -> None:
+        table = Table(
+            {
+                "col1": [0.0, 0.5, 1.0],
+            },
+        )
+
+        transformer = Discretizer().fit(table, None)
+        transformed_table = transformer.transform(table)
+        transformer.inverse_transform(transformed_table)
+
+        expected = Table(
+            {
+                "col1": [0.0, 0.5, 1.0],
+            },
+        )
+
+        assert transformed_table == expected
+
+    def test_should_raise_if_not_fitted(self) -> None:
+        table = Table(
+            {
+                "col1": [0.0, 5.0, 5.0, 10.0],
+            },
+        )
+
+        transformer = Discretizer()
+
+        with pytest.raises(TransformerNotFittedError):
+            transformer.inverse_transform(table)

From d88cdec6e7fdd9c0366da1d4f6d13244a82d1e19 Mon Sep 17 00:00:00 2001
From: methr0 <s6tameth@uni-bonn.de>
Date: Fri, 26 May 2023 17:16:24 +0200
Subject: [PATCH 03/29] added Discretizer to init file remove warnings remove
 inverse_transform bc the Discretizer isn't invertable

---
 .../data/tabular/transformation/__init__.py   |  2 +
 .../tabular/transformation/_discretizer.py    | 32 --------
 .../transformation/test_discretizer.py        | 74 ++-----------------
 3 files changed, 7 insertions(+), 101 deletions(-)

diff --git a/src/safeds/data/tabular/transformation/__init__.py b/src/safeds/data/tabular/transformation/__init__.py
index e8af96cd7..07c4b7f38 100644
--- a/src/safeds/data/tabular/transformation/__init__.py
+++ b/src/safeds/data/tabular/transformation/__init__.py
@@ -1,5 +1,6 @@
 """Classes for transforming tabular data."""
 
+from ._discretizer import Discretizer
 from ._imputer import Imputer
 from ._label_encoder import LabelEncoder
 from ._one_hot_encoder import OneHotEncoder
@@ -13,4 +14,5 @@
     "InvertibleTableTransformer",
     "TableTransformer",
     "RangeScaler",
+    "Discretizer"
 ]
diff --git a/src/safeds/data/tabular/transformation/_discretizer.py b/src/safeds/data/tabular/transformation/_discretizer.py
index cf2a37119..b4fb97d8a 100644
--- a/src/safeds/data/tabular/transformation/_discretizer.py
+++ b/src/safeds/data/tabular/transformation/_discretizer.py
@@ -101,36 +101,6 @@ def transform(self, table: Table) -> Table:
         data[self._column_names] = self._wrapped_transformer.transform(data[self._column_names])
         return Table._from_pandas_dataframe(data)
 
-    def inverse_transform(self, transformed_table: Table) -> Table:
-        """
-        Transform discretized data back to original feature space.
-
-        Note that this function does not regenerate the original data due to discretization rounding.
-        The table is not modified.
-
-        Parameters
-        ----------
-        transformed_table : Table
-            The table to be transformed back to the original version.
-
-        Returns
-        -------
-        table : Table
-            The original table.
-
-        Raises
-        ------
-        TransformerNotFittedError
-            If the transformer has not been fitted yet.
-        """
-        # Transformer has not been fitted yet
-        if self._wrapped_transformer is None or self._column_names is None:
-            raise TransformerNotFittedError
-
-        data = transformed_table._data.copy()
-        data.columns = transformed_table.column_names
-        data[self._column_names] = self._wrapped_transformer.inverse_transform(data[self._column_names])
-        return Table._from_pandas_dataframe(data)
 
     def is_fitted(self) -> bool:
         """
@@ -157,7 +127,6 @@ def get_names_of_added_columns(self) -> list[str]:
         TransformerNotFittedError
             If the transformer has not been fitted yet.
         """
-        warnings.warn("Discretizer only changes data within columns, but does not add any columns.", stacklevel=1)
         if not self.is_fitted():
             raise TransformerNotFittedError
         return []
@@ -195,7 +164,6 @@ def get_names_of_removed_columns(self) -> list[str]:
         TransformerNotFittedError
             If the transformer has not been fitted yet.
         """
-        warnings.warn("Discretizer only changes data within columns, but does not remove any columns.", stacklevel=1)
         if not self.is_fitted():
             raise TransformerNotFittedError
         return []
diff --git a/tests/safeds/data/tabular/transformation/test_discretizer.py b/tests/safeds/data/tabular/transformation/test_discretizer.py
index 40600ce6c..c5701cd66 100644
--- a/tests/safeds/data/tabular/transformation/test_discretizer.py
+++ b/tests/safeds/data/tabular/transformation/test_discretizer.py
@@ -167,7 +167,7 @@ def test_should_return_transformed_table_with_correct_number_of_bins(
         number_of_bins: int,
         expected: Table,
     ) -> None:
-        print(Discretizer(number_of_bins).fit_and_transform(table, ["col1"]))
+
         assert Discretizer(number_of_bins).fit_and_transform(table, ["col1"]) == expected
 
     def test_should_not_change_original_table(self) -> None:
@@ -189,10 +189,7 @@ def test_should_not_change_original_table(self) -> None:
 
     def test_get_names_of_added_columns(self) -> None:
         transformer = Discretizer()
-        with pytest.warns(
-            UserWarning,
-            match="Discretizer only changes data within columns, but does not add any columns.",
-        ), pytest.raises(TransformerNotFittedError):
+        with pytest.raises(TransformerNotFittedError):
             transformer.get_names_of_added_columns()
 
         table = Table(
@@ -201,11 +198,7 @@ def test_get_names_of_added_columns(self) -> None:
             },
         )
         transformer = transformer.fit(table, None)
-        with pytest.warns(
-            UserWarning,
-            match="Discretizer only changes data within columns, but does not add any columns.",
-        ):
-            assert transformer.get_names_of_added_columns() == []
+        assert transformer.get_names_of_added_columns() == []
 
     def test_get_names_of_changed_columns(self) -> None:
         transformer = Discretizer()
@@ -221,10 +214,7 @@ def test_get_names_of_changed_columns(self) -> None:
 
     def test_get_names_of_removed_columns(self) -> None:
         transformer = Discretizer()
-        with pytest.warns(
-            UserWarning,
-            match="Discretizer only changes data within columns, but does not remove any columns.",
-        ), pytest.raises(TransformerNotFittedError):
+        with pytest.raises(TransformerNotFittedError):
             transformer.get_names_of_removed_columns()
 
         table = Table(
@@ -233,58 +223,4 @@ def test_get_names_of_removed_columns(self) -> None:
             },
         )
         transformer = transformer.fit(table, None)
-        with pytest.warns(
-            UserWarning,
-            match="Discretizer only changes data within columns, but does not remove any columns.",
-        ):
-            assert transformer.get_names_of_removed_columns() == []
-
-
-class TestInverseTransform:
-    # inverse_transform doesn't regenerate the old table, it just transforms the discretized data back to original feature space
-    # need to test if the features are the same
-    @pytest.mark.parametrize(
-        "table",
-        [
-            Table(
-                {
-                    "col1": [0.0, 5.0, 5.0, 10.0],
-                },
-            ),
-        ],
-    )
-    def test_should_return_original_table(self, table: Table) -> None:
-        transformer = Discretizer().fit(table, None)
-
-        assert transformer.inverse_transform(transformer.transform(table)) == table
-
-    def test_should_not_change_transformed_table(self) -> None:
-        table = Table(
-            {
-                "col1": [0.0, 0.5, 1.0],
-            },
-        )
-
-        transformer = Discretizer().fit(table, None)
-        transformed_table = transformer.transform(table)
-        transformer.inverse_transform(transformed_table)
-
-        expected = Table(
-            {
-                "col1": [0.0, 0.5, 1.0],
-            },
-        )
-
-        assert transformed_table == expected
-
-    def test_should_raise_if_not_fitted(self) -> None:
-        table = Table(
-            {
-                "col1": [0.0, 5.0, 5.0, 10.0],
-            },
-        )
-
-        transformer = Discretizer()
-
-        with pytest.raises(TransformerNotFittedError):
-            transformer.inverse_transform(table)
+        assert transformer.get_names_of_removed_columns() == []

From 7a21a52f0d33833324c07a2e266e5414f7087eeb Mon Sep 17 00:00:00 2001
From: megalinter-bot <129584137+megalinter-bot@users.noreply.github.com>
Date: Fri, 26 May 2023 15:18:32 +0000
Subject: [PATCH 04/29] style: apply automated linter fixes

---
 src/safeds/data/tabular/transformation/__init__.py        | 2 +-
 src/safeds/data/tabular/transformation/_discretizer.py    | 3 ---
 .../data/tabular/transformation/test_discretizer.py       | 8 +++-----
 3 files changed, 4 insertions(+), 9 deletions(-)

diff --git a/src/safeds/data/tabular/transformation/__init__.py b/src/safeds/data/tabular/transformation/__init__.py
index 07c4b7f38..286219667 100644
--- a/src/safeds/data/tabular/transformation/__init__.py
+++ b/src/safeds/data/tabular/transformation/__init__.py
@@ -14,5 +14,5 @@
     "InvertibleTableTransformer",
     "TableTransformer",
     "RangeScaler",
-    "Discretizer"
+    "Discretizer",
 ]
diff --git a/src/safeds/data/tabular/transformation/_discretizer.py b/src/safeds/data/tabular/transformation/_discretizer.py
index b4fb97d8a..89e44e259 100644
--- a/src/safeds/data/tabular/transformation/_discretizer.py
+++ b/src/safeds/data/tabular/transformation/_discretizer.py
@@ -1,7 +1,5 @@
 from __future__ import annotations
 
-import warnings
-
 from sklearn.preprocessing import KBinsDiscretizer as sk_KBinsDiscretizer
 
 from safeds.data.tabular.containers import Table
@@ -101,7 +99,6 @@ def transform(self, table: Table) -> Table:
         data[self._column_names] = self._wrapped_transformer.transform(data[self._column_names])
         return Table._from_pandas_dataframe(data)
 
-
     def is_fitted(self) -> bool:
         """
         Check if the transformer is fitted.
diff --git a/tests/safeds/data/tabular/transformation/test_discretizer.py b/tests/safeds/data/tabular/transformation/test_discretizer.py
index c5701cd66..894b6f266 100644
--- a/tests/safeds/data/tabular/transformation/test_discretizer.py
+++ b/tests/safeds/data/tabular/transformation/test_discretizer.py
@@ -112,13 +112,13 @@ class TestFitAndTransform:
                 ["col1"],
                 Table(
                     {
-                        "col1": ["(0, 0)\t1.0", "(0, 2)\t1.0","(0, 2)\t1.0", "(0, 3)\t1.0"],
+                        "col1": ["(0, 0)\t1.0", "(0, 2)\t1.0", "(0, 2)\t1.0", "(0, 3)\t1.0"],
                         "col2": [0.0, 5.0, 5.0, 10.0],
                     },
                 ),
             ),
         ],
-        ids=["None", "col1"]
+        ids=["None", "col1"],
     )
     def test_should_return_transformed_table(
         self,
@@ -126,7 +126,6 @@ def test_should_return_transformed_table(
         column_names: list[str] | None,
         expected: Table,
     ) -> None:
-
         assert Discretizer().fit_and_transform(table, column_names) == expected
 
     @pytest.mark.parametrize(
@@ -159,7 +158,7 @@ def test_should_return_transformed_table(
                 ),
             ),
         ],
-        ids=["2", "10"]
+        ids=["2", "10"],
     )
     def test_should_return_transformed_table_with_correct_number_of_bins(
         self,
@@ -167,7 +166,6 @@ def test_should_return_transformed_table_with_correct_number_of_bins(
         number_of_bins: int,
         expected: Table,
     ) -> None:
-
         assert Discretizer(number_of_bins).fit_and_transform(table, ["col1"]) == expected
 
     def test_should_not_change_original_table(self) -> None:

From 432fde4318026cf1a3abbd9a48eddb43ef64edd4 Mon Sep 17 00:00:00 2001
From: methr0 <s6tameth@uni-bonn.de>
Date: Fri, 26 May 2023 17:27:59 +0200
Subject: [PATCH 05/29] removed comment

---
 tests/safeds/data/tabular/transformation/test_discretizer.py | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/tests/safeds/data/tabular/transformation/test_discretizer.py b/tests/safeds/data/tabular/transformation/test_discretizer.py
index c5701cd66..27a8e0761 100644
--- a/tests/safeds/data/tabular/transformation/test_discretizer.py
+++ b/tests/safeds/data/tabular/transformation/test_discretizer.py
@@ -1,6 +1,6 @@
 import pytest
 from safeds.data.tabular.containers import Table
-from safeds.data.tabular.transformation._discretizer import Discretizer
+from safeds.data.tabular.transformation import Discretizer
 from safeds.exceptions import TransformerNotFittedError, UnknownColumnNameError
 
 
@@ -85,7 +85,6 @@ def test_should_return_true_after_fitting(self) -> None:
 
 
 class TestFitAndTransform:
-    # the return value has a formate with "(0,int)\t1.0" and I don't understand how that happens and how the test should look like...
     @pytest.mark.parametrize(
         ("table", "column_names", "expected"),
         [

From 8ff87bb22d31d462e28c24b3215db804519c59e4 Mon Sep 17 00:00:00 2001
From: methr0 <s6tameth@uni-bonn.de>
Date: Fri, 9 Jun 2023 11:15:16 +0200
Subject: [PATCH 06/29] trying to fix the test but it doesn't work

---
 tests/safeds/data/tabular/transformation/test_discretizer.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tests/safeds/data/tabular/transformation/test_discretizer.py b/tests/safeds/data/tabular/transformation/test_discretizer.py
index bc58a425f..94ab2ef60 100644
--- a/tests/safeds/data/tabular/transformation/test_discretizer.py
+++ b/tests/safeds/data/tabular/transformation/test_discretizer.py
@@ -97,7 +97,7 @@ class TestFitAndTransform:
                 None,
                 Table(
                     {
-                        "col1": [0.0, 5.0, 5.0, 10.0],
+                        "col1": ["  (0, 0)\t1.0", "  (0, 2)\t1.0", "  (0, 2)\t1.0", "  (0, 3)\t1.0"],
                     },
                 ),
             ),
@@ -111,7 +111,7 @@ class TestFitAndTransform:
                 ["col1"],
                 Table(
                     {
-                        "col1": ["(0, 0)\t1.0", "(0, 2)\t1.0", "(0, 2)\t1.0", "(0, 3)\t1.0"],
+                        "col1": ["  (0, 0)\t1.0", "  (0, 2)\t1.0", "  (0, 2)\t1.0", "  (0, 3)\t1.0"],
                         "col2": [0.0, 5.0, 5.0, 10.0],
                     },
                 ),

From 2e8cf275ad5f00a2a008a74dd0119cf9c9c48465 Mon Sep 17 00:00:00 2001
From: methr0 <s6tameth@uni-bonn.de>
Date: Fri, 23 Jun 2023 09:30:20 +0200
Subject: [PATCH 07/29] requested changes

---
 src/safeds/data/tabular/transformation/_discretizer.py      | 6 +++---
 .../safeds/data/tabular/transformation/test_discretizer.py  | 4 ++--
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/safeds/data/tabular/transformation/_discretizer.py b/src/safeds/data/tabular/transformation/_discretizer.py
index 89e44e259..b12e3bed2 100644
--- a/src/safeds/data/tabular/transformation/_discretizer.py
+++ b/src/safeds/data/tabular/transformation/_discretizer.py
@@ -28,7 +28,7 @@ def __init__(self, number_of_bins: float = 5):
 
         if number_of_bins < 2:
             raise ValueError("Parameter 'number_of_bins' must be >= 2.")
-        self.number_of_bins = number_of_bins
+        self._number_of_bins = number_of_bins
 
     def fit(self, table: Table, column_names: list[str] | None) -> Discretizer:
         """
@@ -55,10 +55,10 @@ def fit(self, table: Table, column_names: list[str] | None) -> Discretizer:
             if len(missing_columns) > 0:
                 raise UnknownColumnNameError(list(missing_columns))
 
-        wrapped_transformer = sk_KBinsDiscretizer(n_bins=self.number_of_bins)
+        wrapped_transformer = sk_KBinsDiscretizer(n_bins=self._number_of_bins, encode="ordinal")
         wrapped_transformer.fit(table._data[column_names])
 
-        result = Discretizer()
+        result = Discretizer(self._number_of_bins)
         result._wrapped_transformer = wrapped_transformer
         result._column_names = column_names
 
diff --git a/tests/safeds/data/tabular/transformation/test_discretizer.py b/tests/safeds/data/tabular/transformation/test_discretizer.py
index 94ab2ef60..b62023a30 100644
--- a/tests/safeds/data/tabular/transformation/test_discretizer.py
+++ b/tests/safeds/data/tabular/transformation/test_discretizer.py
@@ -97,7 +97,7 @@ class TestFitAndTransform:
                 None,
                 Table(
                     {
-                        "col1": ["  (0, 0)\t1.0", "  (0, 2)\t1.0", "  (0, 2)\t1.0", "  (0, 3)\t1.0"],
+                        "col1": [0.0, 2.0, 2.0, 3.0],
                     },
                 ),
             ),
@@ -111,7 +111,7 @@ class TestFitAndTransform:
                 ["col1"],
                 Table(
                     {
-                        "col1": ["  (0, 0)\t1.0", "  (0, 2)\t1.0", "  (0, 2)\t1.0", "  (0, 3)\t1.0"],
+                        "col1": [0.0, 2.0, 2.0, 3.0],
                         "col2": [0.0, 5.0, 5.0, 10.0],
                     },
                 ),

From a3e46bbb3f7480dc6cf456f50668b6492d50ff16 Mon Sep 17 00:00:00 2001
From: methr0 <s6tameth@uni-bonn.de>
Date: Fri, 23 Jun 2023 11:04:41 +0200
Subject: [PATCH 08/29] requested changes

---
 src/safeds/data/tabular/transformation/_discretizer.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/safeds/data/tabular/transformation/_discretizer.py b/src/safeds/data/tabular/transformation/_discretizer.py
index b12e3bed2..c06816f9c 100644
--- a/src/safeds/data/tabular/transformation/_discretizer.py
+++ b/src/safeds/data/tabular/transformation/_discretizer.py
@@ -3,13 +3,13 @@
 from sklearn.preprocessing import KBinsDiscretizer as sk_KBinsDiscretizer
 
 from safeds.data.tabular.containers import Table
-from safeds.data.tabular.transformation._table_transformer import TableTransformer
+from safeds.data.tabular.transformation import TableTransformer
 from safeds.exceptions import TransformerNotFittedError, UnknownColumnNameError
 
 
 class Discretizer(TableTransformer):
     """
-    The Discretizer transforms replaces a continuous variable by a variable that only has a finite amount of values.
+    The Discretizer bins continuous data into intervals.
 
     Parameters
     ----------

From b33a95f433be1003f1ec238c9193bb5e52fbade5 Mon Sep 17 00:00:00 2001
From: methr0 <s6tameth@uni-bonn.de>
Date: Fri, 23 Jun 2023 11:26:03 +0200
Subject: [PATCH 09/29] import changes

---
 src/safeds/data/tabular/transformation/_discretizer.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/safeds/data/tabular/transformation/_discretizer.py b/src/safeds/data/tabular/transformation/_discretizer.py
index c06816f9c..d5d71b3ee 100644
--- a/src/safeds/data/tabular/transformation/_discretizer.py
+++ b/src/safeds/data/tabular/transformation/_discretizer.py
@@ -3,7 +3,7 @@
 from sklearn.preprocessing import KBinsDiscretizer as sk_KBinsDiscretizer
 
 from safeds.data.tabular.containers import Table
-from safeds.data.tabular.transformation import TableTransformer
+from safeds.data.tabular.transformation._table_transformer import TableTransformer
 from safeds.exceptions import TransformerNotFittedError, UnknownColumnNameError
 
 

From b3d6baf65b1e6fb71907d061c7c8e9d8e11c1dc2 Mon Sep 17 00:00:00 2001
From: methr0 <s6tameth@uni-bonn.de>
Date: Fri, 30 Jun 2023 10:53:23 +0200
Subject: [PATCH 10/29] add ValueError and NonNumericColumnError and test them

---
 .../tabular/transformation/_discretizer.py    | 29 +++++++
 .../transformation/test_discretizer.py        | 81 +++++++++++++++----
 2 files changed, 94 insertions(+), 16 deletions(-)

diff --git a/src/safeds/data/tabular/transformation/_discretizer.py b/src/safeds/data/tabular/transformation/_discretizer.py
index d5d71b3ee..ab6d377e2 100644
--- a/src/safeds/data/tabular/transformation/_discretizer.py
+++ b/src/safeds/data/tabular/transformation/_discretizer.py
@@ -6,6 +6,8 @@
 from safeds.data.tabular.transformation._table_transformer import TableTransformer
 from safeds.exceptions import TransformerNotFittedError, UnknownColumnNameError
 
+from src.safeds.exceptions._data import NonNumericColumnError
+
 
 class Discretizer(TableTransformer):
     """
@@ -47,10 +49,26 @@ def fit(self, table: Table, column_names: list[str] | None) -> Discretizer:
         -------
         fitted_transformer : TableTransformer
             The fitted transformer.
+
+        Raises
+        ------
+        ValueError
+            If the table is empty.
+        NonNumericColumnError
+            If one of the columns, that should be fitted is not numeric.
+        UnknownColumnNameError
+            If one of the columns, that should be fitted is not in the table.
         """
+        if table.number_of_rows == 0:
+            raise ValueError("The Discretizer cannot be fitted because the table contains 0 rows")
+
         if column_names is None:
             column_names = table.column_names
         else:
+            for column in column_names:
+                if not table.get_column(column).type.is_numeric():
+                    raise NonNumericColumnError(f"{column} is of type {table.get_column(column).type}.")
+
             missing_columns = set(column_names) - set(table.column_names)
             if len(missing_columns) > 0:
                 raise UnknownColumnNameError(list(missing_columns))
@@ -84,11 +102,22 @@ def transform(self, table: Table) -> Table:
         ------
         TransformerNotFittedError
             If the transformer has not been fitted yet.
+        ValueError
+            If the table is empty.
+        NonNumericColumnError
+            If one of the columns, that should be fitted is not numeric.
         """
         # Transformer has not been fitted yet
         if self._wrapped_transformer is None or self._column_names is None:
             raise TransformerNotFittedError
 
+        if table.number_of_rows == 0:
+            raise ValueError("The table cannot be transformed because it contains 0 rows")
+
+        for column in self._column_names:
+            if not table.get_column(column).type.is_numeric():
+                raise NonNumericColumnError(f"{column} is of type {table.get_column(column).type}.")
+
         # Input table does not contain all columns used to fit the transformer
         missing_columns = set(self._column_names) - set(table.column_names)
         if len(missing_columns) > 0:
diff --git a/tests/safeds/data/tabular/transformation/test_discretizer.py b/tests/safeds/data/tabular/transformation/test_discretizer.py
index b62023a30..15b4f2716 100644
--- a/tests/safeds/data/tabular/transformation/test_discretizer.py
+++ b/tests/safeds/data/tabular/transformation/test_discretizer.py
@@ -3,6 +3,8 @@
 from safeds.data.tabular.transformation import Discretizer
 from safeds.exceptions import TransformerNotFittedError, UnknownColumnNameError
 
+from src.safeds.exceptions._data import NonNumericColumnError
+
 
 class TestInit:
     def test_should_raise_value_error(self) -> None:
@@ -11,14 +13,38 @@ def test_should_raise_value_error(self) -> None:
 
 
 class TestFit:
-    def test_should_raise_if_column_not_found(self) -> None:
-        table = Table(
-            {
-                "col1": [0.0, 5.0, 10.0],
-            },
-        )
-
-        with pytest.raises(UnknownColumnNameError):
+    @pytest.mark.parametrize(
+        ("table", "error", "error_message"),
+        [
+            (
+                Table(
+                    {
+                        "col1": [0.0, 5.0, 5.0, 10.0],
+                    },
+                ),
+                UnknownColumnNameError,
+                r"Could not find column\(s\) 'col2'"
+            ),
+            (
+                Table(),
+                ValueError,
+                "The Discretizer cannot be fitted because the table contains 0 rows"
+            ),
+            (
+                Table(
+                    {
+                        "col1": [0.0, 5.0, 5.0, 10.0],
+                        "col2": ["a", "b", "c", "d"],
+                    },
+                ),
+                NonNumericColumnError,
+                f"Tried to do a numerical operation on one or multiple non-numerical columns: \ncol2 is of type String."
+            ),
+        ],
+        ids=["UnknownColumnNameError", "ValueError", "NonNumericColumnError"],
+    )
+    def test_should_raise_errors(self, table: Table, error: type[Exception], error_message: str) -> None:
+        with pytest.raises(error, match=error_message):
             Discretizer().fit(table, ["col2"])
 
     def test_should_not_change_original_transformer(self) -> None:
@@ -36,7 +62,36 @@ def test_should_not_change_original_transformer(self) -> None:
 
 
 class TestTransform:
-    def test_should_raise_if_column_not_found(self) -> None:
+    @pytest.mark.parametrize(
+        ("table_to_transform", "error", "error_message"),
+        [
+            (
+                Table(
+                    {
+                        "col2": ["a", "b", "c"],
+                    },
+                ),
+                UnknownColumnNameError,
+                r"Could not find column\(s\) 'col1'"
+            ),
+            (
+                Table(),
+                ValueError,
+                "The table cannot be transformed because it contains 0 rows"
+            ),
+            (
+                Table(
+                    {
+                        "col1": ["a", "b", "c", "d"],
+                    },
+                ),
+                NonNumericColumnError,
+                f"Tried to do a numerical operation on one or multiple non-numerical columns: \ncol1 is of type String."
+            ),
+        ],
+        ids=["UnknownColumnNameError", "ValueError", "NonNumericColumnError"],
+    )
+    def test_should_raise_errors(self, table_to_transform: Table, error: type[Exception], error_message: str) -> None:
         table_to_fit = Table(
             {
                 "col1": [0.0, 5.0, 10.0],
@@ -45,13 +100,7 @@ def test_should_raise_if_column_not_found(self) -> None:
 
         transformer = Discretizer().fit(table_to_fit, None)
 
-        table_to_transform = Table(
-            {
-                "col2": ["a", "b", "c"],
-            },
-        )
-
-        with pytest.raises(UnknownColumnNameError):
+        with pytest.raises(error, match=error_message):
             transformer.transform(table_to_transform)
 
     def test_should_raise_if_not_fitted(self) -> None:

From 0435b5592cea827087697be77eec9e51669c60f2 Mon Sep 17 00:00:00 2001
From: methr0 <s6tameth@uni-bonn.de>
Date: Fri, 30 Jun 2023 10:58:34 +0200
Subject: [PATCH 11/29] fixed import

---
 src/safeds/data/tabular/transformation/_discretizer.py       | 5 +----
 tests/safeds/data/tabular/transformation/test_discretizer.py | 4 +---
 2 files changed, 2 insertions(+), 7 deletions(-)

diff --git a/src/safeds/data/tabular/transformation/_discretizer.py b/src/safeds/data/tabular/transformation/_discretizer.py
index ab6d377e2..991636971 100644
--- a/src/safeds/data/tabular/transformation/_discretizer.py
+++ b/src/safeds/data/tabular/transformation/_discretizer.py
@@ -4,10 +4,7 @@
 
 from safeds.data.tabular.containers import Table
 from safeds.data.tabular.transformation._table_transformer import TableTransformer
-from safeds.exceptions import TransformerNotFittedError, UnknownColumnNameError
-
-from src.safeds.exceptions._data import NonNumericColumnError
-
+from safeds.exceptions import TransformerNotFittedError, UnknownColumnNameError, NonNumericColumnError
 
 class Discretizer(TableTransformer):
     """
diff --git a/tests/safeds/data/tabular/transformation/test_discretizer.py b/tests/safeds/data/tabular/transformation/test_discretizer.py
index 15b4f2716..a4d360c2e 100644
--- a/tests/safeds/data/tabular/transformation/test_discretizer.py
+++ b/tests/safeds/data/tabular/transformation/test_discretizer.py
@@ -1,9 +1,7 @@
 import pytest
 from safeds.data.tabular.containers import Table
 from safeds.data.tabular.transformation import Discretizer
-from safeds.exceptions import TransformerNotFittedError, UnknownColumnNameError
-
-from src.safeds.exceptions._data import NonNumericColumnError
+from safeds.exceptions import TransformerNotFittedError, UnknownColumnNameError, NonNumericColumnError
 
 
 class TestInit:

From cf55a5e83a85ed4e6b57bbcf2d7008439ee1a6c0 Mon Sep 17 00:00:00 2001
From: megalinter-bot <129584137+megalinter-bot@users.noreply.github.com>
Date: Fri, 30 Jun 2023 09:00:24 +0000
Subject: [PATCH 12/29] style: apply automated linter fixes

---
 .../tabular/transformation/_discretizer.py    |  3 +-
 .../transformation/test_discretizer.py        | 28 +++++++++----------
 2 files changed, 15 insertions(+), 16 deletions(-)

diff --git a/src/safeds/data/tabular/transformation/_discretizer.py b/src/safeds/data/tabular/transformation/_discretizer.py
index 991636971..41d6b06ad 100644
--- a/src/safeds/data/tabular/transformation/_discretizer.py
+++ b/src/safeds/data/tabular/transformation/_discretizer.py
@@ -4,7 +4,8 @@
 
 from safeds.data.tabular.containers import Table
 from safeds.data.tabular.transformation._table_transformer import TableTransformer
-from safeds.exceptions import TransformerNotFittedError, UnknownColumnNameError, NonNumericColumnError
+from safeds.exceptions import NonNumericColumnError, TransformerNotFittedError, UnknownColumnNameError
+
 
 class Discretizer(TableTransformer):
     """
diff --git a/tests/safeds/data/tabular/transformation/test_discretizer.py b/tests/safeds/data/tabular/transformation/test_discretizer.py
index a4d360c2e..c59640cd4 100644
--- a/tests/safeds/data/tabular/transformation/test_discretizer.py
+++ b/tests/safeds/data/tabular/transformation/test_discretizer.py
@@ -1,7 +1,7 @@
 import pytest
 from safeds.data.tabular.containers import Table
 from safeds.data.tabular.transformation import Discretizer
-from safeds.exceptions import TransformerNotFittedError, UnknownColumnNameError, NonNumericColumnError
+from safeds.exceptions import NonNumericColumnError, TransformerNotFittedError, UnknownColumnNameError
 
 
 class TestInit:
@@ -21,13 +21,9 @@ class TestFit:
                     },
                 ),
                 UnknownColumnNameError,
-                r"Could not find column\(s\) 'col2'"
-            ),
-            (
-                Table(),
-                ValueError,
-                "The Discretizer cannot be fitted because the table contains 0 rows"
+                r"Could not find column\(s\) 'col2'",
             ),
+            (Table(), ValueError, "The Discretizer cannot be fitted because the table contains 0 rows"),
             (
                 Table(
                     {
@@ -36,7 +32,10 @@ class TestFit:
                     },
                 ),
                 NonNumericColumnError,
-                f"Tried to do a numerical operation on one or multiple non-numerical columns: \ncol2 is of type String."
+                (
+                    "Tried to do a numerical operation on one or multiple non-numerical columns: \ncol2 is of type"
+                    " String."
+                ),
             ),
         ],
         ids=["UnknownColumnNameError", "ValueError", "NonNumericColumnError"],
@@ -70,13 +69,9 @@ class TestTransform:
                     },
                 ),
                 UnknownColumnNameError,
-                r"Could not find column\(s\) 'col1'"
-            ),
-            (
-                Table(),
-                ValueError,
-                "The table cannot be transformed because it contains 0 rows"
+                r"Could not find column\(s\) 'col1'",
             ),
+            (Table(), ValueError, "The table cannot be transformed because it contains 0 rows"),
             (
                 Table(
                     {
@@ -84,7 +79,10 @@ class TestTransform:
                     },
                 ),
                 NonNumericColumnError,
-                f"Tried to do a numerical operation on one or multiple non-numerical columns: \ncol1 is of type String."
+                (
+                    "Tried to do a numerical operation on one or multiple non-numerical columns: \ncol1 is of type"
+                    " String."
+                ),
             ),
         ],
         ids=["UnknownColumnNameError", "ValueError", "NonNumericColumnError"],

From 4b58a0d625e1c7b553a8729351d8ae719fc3644f Mon Sep 17 00:00:00 2001
From: megalinter-bot <129584137+megalinter-bot@users.noreply.github.com>
Date: Fri, 30 Jun 2023 09:02:08 +0000
Subject: [PATCH 13/29] style: apply automated linter fixes

---
 .../data/tabular/transformation/test_discretizer.py    | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/tests/safeds/data/tabular/transformation/test_discretizer.py b/tests/safeds/data/tabular/transformation/test_discretizer.py
index c59640cd4..3f449f6d5 100644
--- a/tests/safeds/data/tabular/transformation/test_discretizer.py
+++ b/tests/safeds/data/tabular/transformation/test_discretizer.py
@@ -32,10 +32,7 @@ class TestFit:
                     },
                 ),
                 NonNumericColumnError,
-                (
-                    "Tried to do a numerical operation on one or multiple non-numerical columns: \ncol2 is of type"
-                    " String."
-                ),
+                "Tried to do a numerical operation on one or multiple non-numerical columns: \ncol2 is of type String.",
             ),
         ],
         ids=["UnknownColumnNameError", "ValueError", "NonNumericColumnError"],
@@ -79,10 +76,7 @@ class TestTransform:
                     },
                 ),
                 NonNumericColumnError,
-                (
-                    "Tried to do a numerical operation on one or multiple non-numerical columns: \ncol1 is of type"
-                    " String."
-                ),
+                "Tried to do a numerical operation on one or multiple non-numerical columns: \ncol1 is of type String.",
             ),
         ],
         ids=["UnknownColumnNameError", "ValueError", "NonNumericColumnError"],

From 4a7520a2f70f113417018bed19d0e4d39298f588 Mon Sep 17 00:00:00 2001
From: methr0 <s6tameth@uni-bonn.de>
Date: Fri, 30 Jun 2023 11:12:52 +0200
Subject: [PATCH 14/29] fixed import

---
 src/safeds/data/tabular/transformation/_discretizer.py       | 3 ++-
 tests/safeds/data/tabular/transformation/test_discretizer.py | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/safeds/data/tabular/transformation/_discretizer.py b/src/safeds/data/tabular/transformation/_discretizer.py
index 991636971..30b3bf271 100644
--- a/src/safeds/data/tabular/transformation/_discretizer.py
+++ b/src/safeds/data/tabular/transformation/_discretizer.py
@@ -4,7 +4,8 @@
 
 from safeds.data.tabular.containers import Table
 from safeds.data.tabular.transformation._table_transformer import TableTransformer
-from safeds.exceptions import TransformerNotFittedError, UnknownColumnNameError, NonNumericColumnError
+from safeds.exceptions import TransformerNotFittedError, UnknownColumnNameError
+from safeds.exceptions import NonNumericColumnError
 
 class Discretizer(TableTransformer):
     """
diff --git a/tests/safeds/data/tabular/transformation/test_discretizer.py b/tests/safeds/data/tabular/transformation/test_discretizer.py
index a4d360c2e..99b82514e 100644
--- a/tests/safeds/data/tabular/transformation/test_discretizer.py
+++ b/tests/safeds/data/tabular/transformation/test_discretizer.py
@@ -1,7 +1,8 @@
 import pytest
 from safeds.data.tabular.containers import Table
 from safeds.data.tabular.transformation import Discretizer
-from safeds.exceptions import TransformerNotFittedError, UnknownColumnNameError, NonNumericColumnError
+from safeds.exceptions import TransformerNotFittedError, UnknownColumnNameError
+from safeds.exceptions import NonNumericColumnError
 
 
 class TestInit:

From 99f139112d1d5792c9e8c1db9201cbf93442aa1f Mon Sep 17 00:00:00 2001
From: megalinter-bot <129584137+megalinter-bot@users.noreply.github.com>
Date: Fri, 30 Jun 2023 09:24:26 +0000
Subject: [PATCH 15/29] style: apply automated linter fixes

---
 src/safeds/data/tabular/transformation/_discretizer.py       | 4 ++--
 tests/safeds/data/tabular/transformation/test_discretizer.py | 3 +--
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/src/safeds/data/tabular/transformation/_discretizer.py b/src/safeds/data/tabular/transformation/_discretizer.py
index 30b3bf271..41d6b06ad 100644
--- a/src/safeds/data/tabular/transformation/_discretizer.py
+++ b/src/safeds/data/tabular/transformation/_discretizer.py
@@ -4,8 +4,8 @@
 
 from safeds.data.tabular.containers import Table
 from safeds.data.tabular.transformation._table_transformer import TableTransformer
-from safeds.exceptions import TransformerNotFittedError, UnknownColumnNameError
-from safeds.exceptions import NonNumericColumnError
+from safeds.exceptions import NonNumericColumnError, TransformerNotFittedError, UnknownColumnNameError
+
 
 class Discretizer(TableTransformer):
     """
diff --git a/tests/safeds/data/tabular/transformation/test_discretizer.py b/tests/safeds/data/tabular/transformation/test_discretizer.py
index 2024036c4..3f449f6d5 100644
--- a/tests/safeds/data/tabular/transformation/test_discretizer.py
+++ b/tests/safeds/data/tabular/transformation/test_discretizer.py
@@ -1,8 +1,7 @@
 import pytest
 from safeds.data.tabular.containers import Table
 from safeds.data.tabular.transformation import Discretizer
-from safeds.exceptions import TransformerNotFittedError, UnknownColumnNameError
-from safeds.exceptions import NonNumericColumnError
+from safeds.exceptions import NonNumericColumnError, TransformerNotFittedError, UnknownColumnNameError
 
 
 class TestInit:

From 93fe3cc973cce031946b13a69aa1e006afaca832 Mon Sep 17 00:00:00 2001
From: methr0 <s6tameth@uni-bonn.de>
Date: Fri, 30 Jun 2023 11:26:04 +0200
Subject: [PATCH 16/29] fixed import

---
 src/safeds/data/tabular/transformation/_discretizer.py       | 3 +--
 tests/safeds/data/tabular/transformation/test_discretizer.py | 3 +--
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/src/safeds/data/tabular/transformation/_discretizer.py b/src/safeds/data/tabular/transformation/_discretizer.py
index 30b3bf271..991636971 100644
--- a/src/safeds/data/tabular/transformation/_discretizer.py
+++ b/src/safeds/data/tabular/transformation/_discretizer.py
@@ -4,8 +4,7 @@
 
 from safeds.data.tabular.containers import Table
 from safeds.data.tabular.transformation._table_transformer import TableTransformer
-from safeds.exceptions import TransformerNotFittedError, UnknownColumnNameError
-from safeds.exceptions import NonNumericColumnError
+from safeds.exceptions import TransformerNotFittedError, UnknownColumnNameError, NonNumericColumnError
 
 class Discretizer(TableTransformer):
     """
diff --git a/tests/safeds/data/tabular/transformation/test_discretizer.py b/tests/safeds/data/tabular/transformation/test_discretizer.py
index 2024036c4..f800645c9 100644
--- a/tests/safeds/data/tabular/transformation/test_discretizer.py
+++ b/tests/safeds/data/tabular/transformation/test_discretizer.py
@@ -1,8 +1,7 @@
 import pytest
 from safeds.data.tabular.containers import Table
 from safeds.data.tabular.transformation import Discretizer
-from safeds.exceptions import TransformerNotFittedError, UnknownColumnNameError
-from safeds.exceptions import NonNumericColumnError
+from safeds.exceptions import TransformerNotFittedError, UnknownColumnNameError, NonNumericColumnError
 
 
 class TestInit:

From 30b54821fc8852e85828af9520e037e96eb82d7d Mon Sep 17 00:00:00 2001
From: methr0 <s6tameth@uni-bonn.de>
Date: Fri, 30 Jun 2023 11:47:53 +0200
Subject: [PATCH 17/29] change order of errors

---
 .../data/tabular/transformation/_discretizer.py  | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/src/safeds/data/tabular/transformation/_discretizer.py b/src/safeds/data/tabular/transformation/_discretizer.py
index 41d6b06ad..011cb8dd4 100644
--- a/src/safeds/data/tabular/transformation/_discretizer.py
+++ b/src/safeds/data/tabular/transformation/_discretizer.py
@@ -63,13 +63,14 @@ def fit(self, table: Table, column_names: list[str] | None) -> Discretizer:
         if column_names is None:
             column_names = table.column_names
         else:
+            missing_columns = set(column_names) - set(table.column_names)
+            if len(missing_columns) > 0:
+                raise UnknownColumnNameError(list(missing_columns))
+
             for column in column_names:
                 if not table.get_column(column).type.is_numeric():
                     raise NonNumericColumnError(f"{column} is of type {table.get_column(column).type}.")
 
-            missing_columns = set(column_names) - set(table.column_names)
-            if len(missing_columns) > 0:
-                raise UnknownColumnNameError(list(missing_columns))
 
         wrapped_transformer = sk_KBinsDiscretizer(n_bins=self._number_of_bins, encode="ordinal")
         wrapped_transformer.fit(table._data[column_names])
@@ -112,15 +113,16 @@ def transform(self, table: Table) -> Table:
         if table.number_of_rows == 0:
             raise ValueError("The table cannot be transformed because it contains 0 rows")
 
-        for column in self._column_names:
-            if not table.get_column(column).type.is_numeric():
-                raise NonNumericColumnError(f"{column} is of type {table.get_column(column).type}.")
-
         # Input table does not contain all columns used to fit the transformer
         missing_columns = set(self._column_names) - set(table.column_names)
         if len(missing_columns) > 0:
             raise UnknownColumnNameError(list(missing_columns))
 
+        for column in self._column_names:
+            if not table.get_column(column).type.is_numeric():
+                raise NonNumericColumnError(f"{column} is of type {table.get_column(column).type}.")
+
+
         data = table._data.copy()
         data.columns = table.column_names
         data[self._column_names] = self._wrapped_transformer.transform(data[self._column_names])

From 7214b6885d4ec3f913315d71ff723dcdc0db5c1f Mon Sep 17 00:00:00 2001
From: megalinter-bot <129584137+megalinter-bot@users.noreply.github.com>
Date: Fri, 30 Jun 2023 09:49:38 +0000
Subject: [PATCH 18/29] style: apply automated linter fixes

---
 src/safeds/data/tabular/transformation/_discretizer.py | 2 --
 1 file changed, 2 deletions(-)

diff --git a/src/safeds/data/tabular/transformation/_discretizer.py b/src/safeds/data/tabular/transformation/_discretizer.py
index 011cb8dd4..646e9ee91 100644
--- a/src/safeds/data/tabular/transformation/_discretizer.py
+++ b/src/safeds/data/tabular/transformation/_discretizer.py
@@ -71,7 +71,6 @@ def fit(self, table: Table, column_names: list[str] | None) -> Discretizer:
                 if not table.get_column(column).type.is_numeric():
                     raise NonNumericColumnError(f"{column} is of type {table.get_column(column).type}.")
 
-
         wrapped_transformer = sk_KBinsDiscretizer(n_bins=self._number_of_bins, encode="ordinal")
         wrapped_transformer.fit(table._data[column_names])
 
@@ -122,7 +121,6 @@ def transform(self, table: Table) -> Table:
             if not table.get_column(column).type.is_numeric():
                 raise NonNumericColumnError(f"{column} is of type {table.get_column(column).type}.")
 
-
         data = table._data.copy()
         data.columns = table.column_names
         data[self._column_names] = self._wrapped_transformer.transform(data[self._column_names])

From cf38032b43d93226b8be2648dbaf548b0d234e58 Mon Sep 17 00:00:00 2001
From: methr0 <s6tameth@uni-bonn.de>
Date: Fri, 30 Jun 2023 15:38:47 +0200
Subject: [PATCH 19/29] requested changes

---
 .../tabular/transformation/_discretizer.py    |  6 +++--
 .../transformation/test_discretizer.py        | 24 +++++++++++++++----
 2 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/src/safeds/data/tabular/transformation/_discretizer.py b/src/safeds/data/tabular/transformation/_discretizer.py
index 011cb8dd4..2508a16ae 100644
--- a/src/safeds/data/tabular/transformation/_discretizer.py
+++ b/src/safeds/data/tabular/transformation/_discretizer.py
@@ -53,7 +53,7 @@ def fit(self, table: Table, column_names: list[str] | None) -> Discretizer:
         ValueError
             If the table is empty.
         NonNumericColumnError
-            If one of the columns, that should be fitted is not numeric.
+            If one of the columns, that should be fitted is non-numeric.
         UnknownColumnNameError
             If one of the columns, that should be fitted is not in the table.
         """
@@ -103,8 +103,10 @@ def transform(self, table: Table) -> Table:
             If the transformer has not been fitted yet.
         ValueError
             If the table is empty.
+        UnknownColumnNameError
+            If one of the columns, that should be transformed is not in the table.
         NonNumericColumnError
-            If one of the columns, that should be fitted is not numeric.
+            If one of the columns, that should be fitted is non-numeric.
         """
         # Transformer has not been fitted yet
         if self._wrapped_transformer is None or self._column_names is None:
diff --git a/tests/safeds/data/tabular/transformation/test_discretizer.py b/tests/safeds/data/tabular/transformation/test_discretizer.py
index 3f449f6d5..52fd31cc4 100644
--- a/tests/safeds/data/tabular/transformation/test_discretizer.py
+++ b/tests/safeds/data/tabular/transformation/test_discretizer.py
@@ -12,7 +12,7 @@ def test_should_raise_value_error(self) -> None:
 
 class TestFit:
     @pytest.mark.parametrize(
-        ("table", "error", "error_message"),
+        ("table", "columns", "error", "error_message"),
         [
             (
                 Table(
@@ -20,10 +20,23 @@ class TestFit:
                         "col1": [0.0, 5.0, 5.0, 10.0],
                     },
                 ),
+                ["col2"],
                 UnknownColumnNameError,
                 r"Could not find column\(s\) 'col2'",
             ),
-            (Table(), ValueError, "The Discretizer cannot be fitted because the table contains 0 rows"),
+            (
+                Table(
+                    {
+                        "col1": [0.0, 5.0, 5.0, 10.0],
+                        "col2": [0.0, 5.0, 5.0, 10.0],
+                        "col3": [0.0, 5.0, 5.0, 10.0],
+                    },
+                ),
+                ["col4", "col5"],
+                UnknownColumnNameError,
+                r"Could not find column\(s\) 'col5', 'col4",
+            ),
+            (Table(), ValueError, ["col2"], "The Discretizer cannot be fitted because the table contains 0 rows"),
             (
                 Table(
                     {
@@ -31,15 +44,16 @@ class TestFit:
                         "col2": ["a", "b", "c", "d"],
                     },
                 ),
+                ["col2"],
                 NonNumericColumnError,
                 "Tried to do a numerical operation on one or multiple non-numerical columns: \ncol2 is of type String.",
             ),
         ],
-        ids=["UnknownColumnNameError", "ValueError", "NonNumericColumnError"],
+        ids=["UnknownColumnNameError", "multiple missing columns", "ValueError", "NonNumericColumnError"],
     )
-    def test_should_raise_errors(self, table: Table, error: type[Exception], error_message: str) -> None:
+    def test_should_raise_errors(self, table: Table, columns: list[str], error: type[Exception], error_message: str) -> None:
         with pytest.raises(error, match=error_message):
-            Discretizer().fit(table, ["col2"])
+            Discretizer().fit(table, columns)
 
     def test_should_not_change_original_transformer(self) -> None:
         table = Table(

From 2a5b687f7172151c7f974288473e94caaa7f71e8 Mon Sep 17 00:00:00 2001
From: methr0 <s6tameth@uni-bonn.de>
Date: Fri, 30 Jun 2023 15:53:25 +0200
Subject: [PATCH 20/29] requested changes

---
 .../transformation/test_discretizer.py        | 28 ++++++++++++++-----
 1 file changed, 21 insertions(+), 7 deletions(-)

diff --git a/tests/safeds/data/tabular/transformation/test_discretizer.py b/tests/safeds/data/tabular/transformation/test_discretizer.py
index 52fd31cc4..8d3953680 100644
--- a/tests/safeds/data/tabular/transformation/test_discretizer.py
+++ b/tests/safeds/data/tabular/transformation/test_discretizer.py
@@ -34,9 +34,9 @@ class TestFit:
                 ),
                 ["col4", "col5"],
                 UnknownColumnNameError,
-                r"Could not find column\(s\) 'col5', 'col4",
+                r"Could not find column\(s\) 'col4, col5'",
             ),
-            (Table(), ValueError, ["col2"], "The Discretizer cannot be fitted because the table contains 0 rows"),
+            (Table(), ["col2"], ValueError, "The Discretizer cannot be fitted because the table contains 0 rows"),
             (
                 Table(
                     {
@@ -52,6 +52,7 @@ class TestFit:
         ids=["UnknownColumnNameError", "multiple missing columns", "ValueError", "NonNumericColumnError"],
     )
     def test_should_raise_errors(self, table: Table, columns: list[str], error: type[Exception], error_message: str) -> None:
+        print(type(error))
         with pytest.raises(error, match=error_message):
             Discretizer().fit(table, columns)
 
@@ -71,7 +72,7 @@ def test_should_not_change_original_transformer(self) -> None:
 
 class TestTransform:
     @pytest.mark.parametrize(
-        ("table_to_transform", "error", "error_message"),
+        ("table_to_transform", "columns", "error", "error_message"),
         [
             (
                 Table(
@@ -79,30 +80,43 @@ class TestTransform:
                         "col2": ["a", "b", "c"],
                     },
                 ),
+                ["col1"],
                 UnknownColumnNameError,
                 r"Could not find column\(s\) 'col1'",
             ),
-            (Table(), ValueError, "The table cannot be transformed because it contains 0 rows"),
+            (
+                Table(
+                    {
+                        "col2": ["a", "b", "c"],
+                    },
+                ),
+                ["col1", "col3"],
+                UnknownColumnNameError,
+                r"Could not find column\(s\) 'col1, col3'",
+            ),
+            (Table(), ["col1", "col3"], ValueError, "The table cannot be transformed because it contains 0 rows"),
             (
                 Table(
                     {
                         "col1": ["a", "b", "c", "d"],
                     },
                 ),
+                ["col1"],
                 NonNumericColumnError,
                 "Tried to do a numerical operation on one or multiple non-numerical columns: \ncol1 is of type String.",
             ),
         ],
-        ids=["UnknownColumnNameError", "ValueError", "NonNumericColumnError"],
+        ids=["UnknownColumnNameError", "multiple missing columns", "ValueError", "NonNumericColumnError"],
     )
-    def test_should_raise_errors(self, table_to_transform: Table, error: type[Exception], error_message: str) -> None:
+    def test_should_raise_errors(self, table_to_transform: Table, columns: list[str], error: type[Exception], error_message: str) -> None:
         table_to_fit = Table(
             {
                 "col1": [0.0, 5.0, 10.0],
+                "col3": [0.0, 5.0, 10.0],
             },
         )
 
-        transformer = Discretizer().fit(table_to_fit, None)
+        transformer = Discretizer().fit(table_to_fit, columns)
 
         with pytest.raises(error, match=error_message):
             transformer.transform(table_to_transform)

From 135aa9edeaff106a2eda1f247c2ccf4724d74fc5 Mon Sep 17 00:00:00 2001
From: methr0 <s6tameth@uni-bonn.de>
Date: Fri, 30 Jun 2023 15:59:13 +0200
Subject: [PATCH 21/29] make linter happy

---
 tests/safeds/data/tabular/transformation/test_discretizer.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/safeds/data/tabular/transformation/test_discretizer.py b/tests/safeds/data/tabular/transformation/test_discretizer.py
index 8d3953680..7b3b40848 100644
--- a/tests/safeds/data/tabular/transformation/test_discretizer.py
+++ b/tests/safeds/data/tabular/transformation/test_discretizer.py
@@ -92,7 +92,7 @@ class TestTransform:
                 ),
                 ["col1", "col3"],
                 UnknownColumnNameError,
-                r"Could not find column\(s\) 'col1, col3'",
+                r"Could not find column\(s\) 'col3, col1'",
             ),
             (Table(), ["col1", "col3"], ValueError, "The table cannot be transformed because it contains 0 rows"),
             (

From 4e482008e729783d15fe50ff2c01ed60f48f10d6 Mon Sep 17 00:00:00 2001
From: methr0 <s6tameth@uni-bonn.de>
Date: Fri, 30 Jun 2023 16:15:30 +0200
Subject: [PATCH 22/29] make linter happy

---
 src/safeds/data/tabular/transformation/_discretizer.py       | 3 ++-
 tests/safeds/data/tabular/transformation/test_discretizer.py | 2 +-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/safeds/data/tabular/transformation/_discretizer.py b/src/safeds/data/tabular/transformation/_discretizer.py
index a1f28065c..75098f270 100644
--- a/src/safeds/data/tabular/transformation/_discretizer.py
+++ b/src/safeds/data/tabular/transformation/_discretizer.py
@@ -117,7 +117,8 @@ def transform(self, table: Table) -> Table:
         # Input table does not contain all columns used to fit the transformer
         missing_columns = set(self._column_names) - set(table.column_names)
         if len(missing_columns) > 0:
-            raise UnknownColumnNameError(list(missing_columns))
+            raise UnknownColumnNameError(sorted(set(missing_columns).intersection(set(table.column_names)),
+                key={val: ix for ix, val in enumerate(missing_columns)}.__getitem__,))
 
         for column in self._column_names:
             if not table.get_column(column).type.is_numeric():
diff --git a/tests/safeds/data/tabular/transformation/test_discretizer.py b/tests/safeds/data/tabular/transformation/test_discretizer.py
index 7b3b40848..8d3953680 100644
--- a/tests/safeds/data/tabular/transformation/test_discretizer.py
+++ b/tests/safeds/data/tabular/transformation/test_discretizer.py
@@ -92,7 +92,7 @@ class TestTransform:
                 ),
                 ["col1", "col3"],
                 UnknownColumnNameError,
-                r"Could not find column\(s\) 'col3, col1'",
+                r"Could not find column\(s\) 'col1, col3'",
             ),
             (Table(), ["col1", "col3"], ValueError, "The table cannot be transformed because it contains 0 rows"),
             (

From c113b59dab2a9f92967b0019c4df4a298fae9cf6 Mon Sep 17 00:00:00 2001
From: methr0 <s6tameth@uni-bonn.de>
Date: Fri, 30 Jun 2023 16:21:47 +0200
Subject: [PATCH 23/29] make linter happy

---
 src/safeds/data/tabular/transformation/_discretizer.py | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/safeds/data/tabular/transformation/_discretizer.py b/src/safeds/data/tabular/transformation/_discretizer.py
index 75098f270..81d6f03ea 100644
--- a/src/safeds/data/tabular/transformation/_discretizer.py
+++ b/src/safeds/data/tabular/transformation/_discretizer.py
@@ -117,8 +117,7 @@ def transform(self, table: Table) -> Table:
         # Input table does not contain all columns used to fit the transformer
         missing_columns = set(self._column_names) - set(table.column_names)
         if len(missing_columns) > 0:
-            raise UnknownColumnNameError(sorted(set(missing_columns).intersection(set(table.column_names)),
-                key={val: ix for ix, val in enumerate(missing_columns)}.__getitem__,))
+            raise UnknownColumnNameError(sorted(missing_columns))
 
         for column in self._column_names:
             if not table.get_column(column).type.is_numeric():

From 1f332aaaf12ded51d21a846c61c8deb2064f1d84 Mon Sep 17 00:00:00 2001
From: methr0 <s6tameth@uni-bonn.de>
Date: Fri, 30 Jun 2023 16:29:42 +0200
Subject: [PATCH 24/29] make linter happy

---
 src/safeds/data/tabular/transformation/_discretizer.py      | 6 ++++--
 .../safeds/data/tabular/transformation/test_discretizer.py  | 4 ++--
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/safeds/data/tabular/transformation/_discretizer.py b/src/safeds/data/tabular/transformation/_discretizer.py
index 81d6f03ea..5a77a089f 100644
--- a/src/safeds/data/tabular/transformation/_discretizer.py
+++ b/src/safeds/data/tabular/transformation/_discretizer.py
@@ -65,7 +65,8 @@ def fit(self, table: Table, column_names: list[str] | None) -> Discretizer:
         else:
             missing_columns = set(column_names) - set(table.column_names)
             if len(missing_columns) > 0:
-                raise UnknownColumnNameError(list(missing_columns))
+                raise UnknownColumnNameError(sorted(missing_columns,
+                    key={val: ix for ix, val in enumerate(column_names)}.__getitem__, ))
 
             for column in column_names:
                 if not table.get_column(column).type.is_numeric():
@@ -117,7 +118,8 @@ def transform(self, table: Table) -> Table:
         # Input table does not contain all columns used to fit the transformer
         missing_columns = set(self._column_names) - set(table.column_names)
         if len(missing_columns) > 0:
-            raise UnknownColumnNameError(sorted(missing_columns))
+            raise UnknownColumnNameError(sorted(missing_columns,
+                key={val: ix for ix, val in enumerate(self._column_names)}.__getitem__,))
 
         for column in self._column_names:
             if not table.get_column(column).type.is_numeric():
diff --git a/tests/safeds/data/tabular/transformation/test_discretizer.py b/tests/safeds/data/tabular/transformation/test_discretizer.py
index 8d3953680..2095c6173 100644
--- a/tests/safeds/data/tabular/transformation/test_discretizer.py
+++ b/tests/safeds/data/tabular/transformation/test_discretizer.py
@@ -90,9 +90,9 @@ class TestTransform:
                         "col2": ["a", "b", "c"],
                     },
                 ),
-                ["col1", "col3"],
+                ["col3", "col1"],
                 UnknownColumnNameError,
-                r"Could not find column\(s\) 'col1, col3'",
+                r"Could not find column\(s\) 'col3, col1'",
             ),
             (Table(), ["col1", "col3"], ValueError, "The table cannot be transformed because it contains 0 rows"),
             (

From 7f0775ec49703b619299a8d411e37fcce46c8025 Mon Sep 17 00:00:00 2001
From: methr0 <s6tameth@uni-bonn.de>
Date: Fri, 30 Jun 2023 16:32:09 +0200
Subject: [PATCH 25/29] make linter happy

---
 tests/safeds/data/tabular/transformation/test_discretizer.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/tests/safeds/data/tabular/transformation/test_discretizer.py b/tests/safeds/data/tabular/transformation/test_discretizer.py
index 2095c6173..629b788a9 100644
--- a/tests/safeds/data/tabular/transformation/test_discretizer.py
+++ b/tests/safeds/data/tabular/transformation/test_discretizer.py
@@ -52,7 +52,6 @@ class TestFit:
         ids=["UnknownColumnNameError", "multiple missing columns", "ValueError", "NonNumericColumnError"],
     )
     def test_should_raise_errors(self, table: Table, columns: list[str], error: type[Exception], error_message: str) -> None:
-        print(type(error))
         with pytest.raises(error, match=error_message):
             Discretizer().fit(table, columns)
 

From 9b5edf030c6c8c3239c11d2d713fa429f57743a8 Mon Sep 17 00:00:00 2001
From: megalinter-bot <129584137+megalinter-bot@users.noreply.github.com>
Date: Fri, 30 Jun 2023 14:33:59 +0000
Subject: [PATCH 26/29] style: apply automated linter fixes

---
 .../data/tabular/transformation/_discretizer.py  | 16 ++++++++++++----
 .../tabular/transformation/test_discretizer.py   |  8 ++++++--
 2 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/src/safeds/data/tabular/transformation/_discretizer.py b/src/safeds/data/tabular/transformation/_discretizer.py
index 5a77a089f..9e9b6187a 100644
--- a/src/safeds/data/tabular/transformation/_discretizer.py
+++ b/src/safeds/data/tabular/transformation/_discretizer.py
@@ -65,8 +65,12 @@ def fit(self, table: Table, column_names: list[str] | None) -> Discretizer:
         else:
             missing_columns = set(column_names) - set(table.column_names)
             if len(missing_columns) > 0:
-                raise UnknownColumnNameError(sorted(missing_columns,
-                    key={val: ix for ix, val in enumerate(column_names)}.__getitem__, ))
+                raise UnknownColumnNameError(
+                    sorted(
+                        missing_columns,
+                        key={val: ix for ix, val in enumerate(column_names)}.__getitem__,
+                    ),
+                )
 
             for column in column_names:
                 if not table.get_column(column).type.is_numeric():
@@ -118,8 +122,12 @@ def transform(self, table: Table) -> Table:
         # Input table does not contain all columns used to fit the transformer
         missing_columns = set(self._column_names) - set(table.column_names)
         if len(missing_columns) > 0:
-            raise UnknownColumnNameError(sorted(missing_columns,
-                key={val: ix for ix, val in enumerate(self._column_names)}.__getitem__,))
+            raise UnknownColumnNameError(
+                sorted(
+                    missing_columns,
+                    key={val: ix for ix, val in enumerate(self._column_names)}.__getitem__,
+                ),
+            )
 
         for column in self._column_names:
             if not table.get_column(column).type.is_numeric():
diff --git a/tests/safeds/data/tabular/transformation/test_discretizer.py b/tests/safeds/data/tabular/transformation/test_discretizer.py
index 629b788a9..dbaa20c07 100644
--- a/tests/safeds/data/tabular/transformation/test_discretizer.py
+++ b/tests/safeds/data/tabular/transformation/test_discretizer.py
@@ -51,7 +51,9 @@ class TestFit:
         ],
         ids=["UnknownColumnNameError", "multiple missing columns", "ValueError", "NonNumericColumnError"],
     )
-    def test_should_raise_errors(self, table: Table, columns: list[str], error: type[Exception], error_message: str) -> None:
+    def test_should_raise_errors(
+        self, table: Table, columns: list[str], error: type[Exception], error_message: str,
+    ) -> None:
         with pytest.raises(error, match=error_message):
             Discretizer().fit(table, columns)
 
@@ -107,7 +109,9 @@ class TestTransform:
         ],
         ids=["UnknownColumnNameError", "multiple missing columns", "ValueError", "NonNumericColumnError"],
     )
-    def test_should_raise_errors(self, table_to_transform: Table, columns: list[str], error: type[Exception], error_message: str) -> None:
+    def test_should_raise_errors(
+        self, table_to_transform: Table, columns: list[str], error: type[Exception], error_message: str,
+    ) -> None:
         table_to_fit = Table(
             {
                 "col1": [0.0, 5.0, 10.0],

From ed00f74a78a1dee2af5eab4abad0b873bb26aa49 Mon Sep 17 00:00:00 2001
From: megalinter-bot <129584137+megalinter-bot@users.noreply.github.com>
Date: Fri, 30 Jun 2023 14:35:42 +0000
Subject: [PATCH 27/29] style: apply automated linter fixes

---
 .../data/tabular/transformation/test_discretizer.py  | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/tests/safeds/data/tabular/transformation/test_discretizer.py b/tests/safeds/data/tabular/transformation/test_discretizer.py
index dbaa20c07..7242d02d1 100644
--- a/tests/safeds/data/tabular/transformation/test_discretizer.py
+++ b/tests/safeds/data/tabular/transformation/test_discretizer.py
@@ -52,7 +52,11 @@ class TestFit:
         ids=["UnknownColumnNameError", "multiple missing columns", "ValueError", "NonNumericColumnError"],
     )
     def test_should_raise_errors(
-        self, table: Table, columns: list[str], error: type[Exception], error_message: str,
+        self,
+        table: Table,
+        columns: list[str],
+        error: type[Exception],
+        error_message: str,
     ) -> None:
         with pytest.raises(error, match=error_message):
             Discretizer().fit(table, columns)
@@ -110,7 +114,11 @@ class TestTransform:
         ids=["UnknownColumnNameError", "multiple missing columns", "ValueError", "NonNumericColumnError"],
     )
     def test_should_raise_errors(
-        self, table_to_transform: Table, columns: list[str], error: type[Exception], error_message: str,
+        self,
+        table_to_transform: Table,
+        columns: list[str],
+        error: type[Exception],
+        error_message: str,
     ) -> None:
         table_to_fit = Table(
             {

From be053052c050a6ac0e588d769001aa195b0e9495 Mon Sep 17 00:00:00 2001
From: methr0 <s6tameth@uni-bonn.de>
Date: Fri, 7 Jul 2023 09:16:38 +0200
Subject: [PATCH 28/29] requested changes, match error message

---
 .../data/tabular/transformation/test_discretizer.py       | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/tests/safeds/data/tabular/transformation/test_discretizer.py b/tests/safeds/data/tabular/transformation/test_discretizer.py
index 629b788a9..ce56d801d 100644
--- a/tests/safeds/data/tabular/transformation/test_discretizer.py
+++ b/tests/safeds/data/tabular/transformation/test_discretizer.py
@@ -129,7 +129,7 @@ def test_should_raise_if_not_fitted(self) -> None:
 
         transformer = Discretizer()
 
-        with pytest.raises(TransformerNotFittedError):
+        with pytest.raises(TransformerNotFittedError, match=r"The transformer has not been fitted yet."):
             transformer.transform(table)
 
 
@@ -252,7 +252,7 @@ def test_should_not_change_original_table(self) -> None:
 
     def test_get_names_of_added_columns(self) -> None:
         transformer = Discretizer()
-        with pytest.raises(TransformerNotFittedError):
+        with pytest.raises(TransformerNotFittedError, match=r"The transformer has not been fitted yet."):
             transformer.get_names_of_added_columns()
 
         table = Table(
@@ -265,7 +265,7 @@ def test_get_names_of_added_columns(self) -> None:
 
     def test_get_names_of_changed_columns(self) -> None:
         transformer = Discretizer()
-        with pytest.raises(TransformerNotFittedError):
+        with pytest.raises(TransformerNotFittedError, match=r"The transformer has not been fitted yet."):
             transformer.get_names_of_changed_columns()
         table = Table(
             {
@@ -277,7 +277,7 @@ def test_get_names_of_changed_columns(self) -> None:
 
     def test_get_names_of_removed_columns(self) -> None:
         transformer = Discretizer()
-        with pytest.raises(TransformerNotFittedError):
+        with pytest.raises(TransformerNotFittedError, match=r"The transformer has not been fitted yet."):
             transformer.get_names_of_removed_columns()
 
         table = Table(

From b2c1b299548cb22f18d4618d9b38061357a98b63 Mon Sep 17 00:00:00 2001
From: methr0 <s6tameth@uni-bonn.de>
Date: Fri, 7 Jul 2023 09:24:39 +0200
Subject: [PATCH 29/29] requested changes

---
 src/safeds/data/tabular/transformation/_discretizer.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/safeds/data/tabular/transformation/_discretizer.py b/src/safeds/data/tabular/transformation/_discretizer.py
index 9e9b6187a..38a6cf0f0 100644
--- a/src/safeds/data/tabular/transformation/_discretizer.py
+++ b/src/safeds/data/tabular/transformation/_discretizer.py
@@ -40,7 +40,7 @@ def fit(self, table: Table, column_names: list[str] | None) -> Discretizer:
         ----------
         table : Table
             The table used to fit the transformer.
-        column_names : Optional[list[str]]
+        column_names : list[str] | None
             The list of columns from the table used to fit the transformer. If `None`, all columns are used.
 
         Returns