Resolve "release v1.2.0"

Closes #257 (closed)

mlair/run_modules/pre_processing.py

@@ -164,7 +164,8 @@ class PreProcessing(RunEnvironment):
                 if df.loc[station_name, meta_data].isnull().any():
                     df.loc[station_name, meta_data] = station.id_class.meta.loc[meta_data].values.flatten()
             df.loc["# Samples", set_name] = df.loc[:, set_name].sum()
-            df.loc["# Stations", set_name] = df.loc[:, set_name].count()
+            assert len(data) == df.loc[:, set_name].count() - 1
+            df.loc["# Stations", set_name] = len(data)
         df[meta_round] = df[meta_round].astype(float).round(precision)
         df.sort_index(inplace=True)
         df = df.reindex(df.index.drop(["# Stations", "# Samples"]).to_list() + ["# Stations", "# Samples"], )