feat: Convert between Excel file and Table (#233)

Closes #138. 
Closes #139 .

### Summary of Changes
Created the methods to_excel_file() and from_excel_file() in Class
Table.

---------

Co-authored-by: megalinter-bot <129584137+megalinter-bot@users.noreply.github.com>
Co-authored-by: patrikguempel <patrikguempel@gmail.com>
Co-authored-by: Lars Reimann <mail@larsreimann.com>
Co-authored-by: patrikguempel <128832338+patrikguempel@users.noreply.github.com>

pyproject.toml

@@ -20,6 +20,7 @@ pandas = "^2.0.0"
 pillow = "^9.5.0"
 scikit-learn = "^1.2.0"
 seaborn = "^0.12.2"
+openpyxl = "^3.1.2"
 
 [tool.poetry.group.dev.dependencies]
 pytest = "^7.2.1"

src/safeds/data/tabular/containers/_table.py

@@ -7,6 +7,7 @@
 
 import matplotlib.pyplot as plt
 import numpy as np
+import openpyxl
 import pandas as pd
 import seaborn as sns
 from pandas import DataFrame
@@ -84,6 +85,33 @@ def from_csv_file(path: str | Path) -> Table:
         except FileNotFoundError as exception:
             raise FileNotFoundError(f'File "{path}" does not exist') from exception
 
+    @staticmethod
+    def from_excel_file(path: str | Path) -> Table:
+        """
+        Read data from an Excel file into a table.
+
+        Parameters
+        ----------
+        path : str | Path
+            The path to the Excel file.
+
+        Returns
+        -------
+        table : Table
+            The table created from the Excel file.
+
+        Raises
+        ------
+        FileNotFoundError
+            If the specified file does not exist.
+        ValueError
+            If the file could not be read.
+        """
+        try:
+            return Table(pd.read_excel(path, engine="openpyxl", usecols=lambda colname: "Unnamed" not in colname))
+        except FileNotFoundError as exception:
+            raise FileNotFoundError(f'File "{path}" does not exist') from exception
+
     @staticmethod
     def from_json_file(path: str | Path) -> Table:
         """
@@ -1242,6 +1270,27 @@ def to_csv_file(self, path: str | Path) -> None:
         data_to_csv.columns = self._schema.column_names
         data_to_csv.to_csv(path, index=False)
 
+    def to_excel_file(self, path: str | Path) -> None:
+        """
+        Write the data from the table into an Excel file.
+
+        If the file and/or the directories do not exist, they will be created. If the file already exists, it will be
+        overwritten.
+
+        Parameters
+        ----------
+        path : str | Path
+            The path to the output file.
+        """
+        # Create Excel metadata in the file
+        tmp_table_file = openpyxl.Workbook()
+        tmp_table_file.save(path)
+
+        Path(path).parent.mkdir(parents=True, exist_ok=True)
+        data_to_excel = self._data.copy()
+        data_to_excel.columns = self._schema.column_names
+        data_to_excel.to_excel(path)
+
     def to_json_file(self, path: str | Path) -> None:
         """
         Write the data from the table into a JSON file.

tests/safeds/data/tabular/containers/_table/test_from_excel_file.py

@@ -0,0 +1,40 @@
+from pathlib import Path
+
+import pytest
+from safeds.data.tabular.containers import Table
+
+from tests.helpers import resolve_resource_path
+
+
+@pytest.mark.parametrize(
+    ("path", "expected"),
+    [
+        (
+            resolve_resource_path("./dummy_excel_file.xlsx"),
+            Table.from_dict(
+                {
+                    "A": [1],
+                    "B": [2],
+                },
+            ),
+        ),
+        (
+            Path(resolve_resource_path("./dummy_excel_file.xlsx")),
+            Table.from_dict(
+                {
+                    "A": [1],
+                    "B": [2],
+                },
+            ),
+        ),
+    ],
+    ids=["string path", "object path"],
+)
+def test_should_create_table_from_excel_file(path: str | Path, expected: Table) -> None:
+    table = Table.from_excel_file(path)
+    assert table == expected
+
+
+def test_should_raise_if_file_not_found() -> None:
+    with pytest.raises(FileNotFoundError):
+        Table.from_excel_file(resolve_resource_path("test_table_from_excel_file_invalid.xls"))

tests/safeds/data/tabular/containers/_table/test_to_excel_file.py

@@ -0,0 +1,26 @@
+from pathlib import Path
+from tempfile import NamedTemporaryFile
+
+from safeds.data.tabular.containers import Table
+
+
+def test_should_create_csv_file_from_table_by_str() -> None:
+    table = Table.from_dict({"col1": ["col1_1"], "col2": ["col2_1"]})
+    with NamedTemporaryFile(suffix=".xlsx") as tmp_table_file:
+        tmp_table_file.close()
+        with Path(tmp_table_file.name).open("w", encoding="utf-8") as tmp_file:
+            table.to_excel_file(tmp_file.name)
+        with Path(tmp_table_file.name).open("r", encoding="utf-8") as tmp_file:
+            table_r = Table.from_excel_file(tmp_file.name)
+    assert table == table_r
+
+
+def test_should_create_csv_file_from_table_by_path() -> None:
+    table = Table.from_dict({"col1": ["col1_1"], "col2": ["col2_1"]})
+    with NamedTemporaryFile(suffix=".xlsx") as tmp_table_file:
+        tmp_table_file.close()
+        with Path(tmp_table_file.name).open("w", encoding="utf-8") as tmp_file:
+            table.to_excel_file(Path(tmp_file.name))
+        with Path(tmp_table_file.name).open("r", encoding="utf-8") as tmp_file:
+            table_r = Table.from_excel_file(Path(tmp_file.name))
+    assert table == table_r