Merge pull request #32 from KatharinaBuelow/newindex

newindex

docs/index.rst

@@ -11,6 +11,8 @@ Welcome to index_calculator's documentation!
    usage
    notebooks
    indices
+   newproject
+   newindex
    contributing
    authors
    api

docs/newindex.rst

@@ -0,0 +1,46 @@
+.. highlight:: shell
+
+=========
+New index
+=========
+
+The index calculation is based on xclim_. Index calculator only calculated indices, which are available in xclim. If you need an index, which is not included in xclim, please integrate it in xclim not here.
+
+First, you need a new index you need to edit two files:
+
+.. code-block:: console
+
+    $ cd index_calculator/tables
+    $ input_vars.json
+    $ metadata.json
+
+
+Second:
+
+.. code-block:: console
+
+    $ cd index_calculator/_indices.py
+    $ _indices.py
+
+
+The easiest way is to copy an exsiting index which is similar to your new one and adjust it to your needs. The naming conventions can de found in xclim_ under indicators (not indices).
+
+At last you need to perform a test:
+
+.. code-block:: console
+
+    $ pip install pytest
+
+
+Please edit test_indices.py and execute
+
+.. code-block:: console
+
+    $ cd tests
+    $ test_indices.py (edit)
+    $ pytest (run)
+
+
+
+
+.. _xclim: https://github.com/Ouranosinc/xclim

docs/newproject.rst

@@ -0,0 +1,18 @@
+.. highlight:: shell
+
+===========
+New project
+===========
+
+For adding your own project you need to change three files.
+
+
+.. code-block:: console
+
+    $ cd index_calculator/tables
+    $ cf_conversion.json
+    $ projects.json
+    $ xcalc.json
+
+
+The easiest way is to copy an exsiting project like e.g. EOBS and edit it according to your needs.

index_calculator/_indices.py

@@ -1259,6 +1259,39 @@ def compute(self, thresh=None, **params):
         return self.compute_climate_indicator(params=params, thresh=thresh)
 
 
+class CMD(ClimateIndicator):
+    """Number of calm days (sfcWind)."""
+
+    def __init__(self):
+        super().__init__()
+        self.thresh = 2
+        self.units = {"thresh": "m s-1"}
+        self.func = xc.atmos.calm_days
+
+    def compute(self, thresh=None, **params):
+        """Calculate number of calm days.
+
+        Parameters
+        ----------
+        thresh: int or string, optional
+            Threshold wind speed below which a day is considered
+            as a calm day (default: 2 m s-1).
+            If type of threshold is an integer the unit is set to m s-1.
+
+        Returns
+        -------
+        xarray.DataArray
+            Number of calm days ( fg > {thresh}).
+
+        Notes
+        -----
+        For more information on the input parameters see:
+            https://xclim.readthedocs.io/en/stable/api.html#xclim.indicators.atmos.calm_days
+
+        """
+        return self.compute_climate_indicator(params=params, thresh=thresh)
+
+
 class SQI(ClimateIndicator):
     """Number of uncomfortable sleep events (tasmin)."""
 

index_calculator/tables/input_vars.json

@@ -79,5 +79,6 @@
     "FGn": "sfcWind",
     "FX": "sfcWindmax",
     "FXx": "sfcWindmax",
-    "FXn": "sfcWindmax"
+    "FXn": "sfcWindmax",
+    "CMD": "sfcWind"
 }

index_calculator/tables/metadata.json

@@ -335,6 +335,12 @@
 	"units": "m s-1",
 	"description": "Minimum of daily maximum wind speed."
     },
+    "CMD": {
+	"standard_name": "days_with_wind_speed_below_threshold",
+	"long_name": "Number of calm days (wind speed < {thresh} m s-2)",
+	"units": "days",
+	"description": "Number of days with daily wind speed below {thresh} m s-2."
+    },
     "CW": {
 	"standard_name": "cold_and_wet_days",
 	"long_name": "Number of cold and wet days",

tests/test_indices.py

@@ -811,3 +811,12 @@ def test_FXx():
         freq="7D",
     )
     np.testing.assert_allclose(result, [23], rtol=1e-03)
+
+
+def test_CMD():
+    idx_class = indices.CMD()
+    result = idx_class.compute(
+        sfcWind=sfcWind_xarray(),
+        freq="7D",
+    )
+    np.testing.assert_allclose(result, [1], rtol=1e-03)