body.exercise: add cardio summary, move cross trainer to a separate file

my/body/exercise/cardio.py

@@ -0,0 +1,50 @@
+'''
+Cardio data, filtered from Endomondo and inferred from other data sources
+'''
+from ...core.pandas import check_dataframe as cdf
+
+import pandas as pd # type: ignore
+
+
+CARDIO     = {
+    'Running',
+    'Running, treadmill',
+    'Cross training',
+    'Walking',
+    'Skating',
+    'Spinning',
+    'Skiing',
+    'Table tennis',
+    'Rope jumping',
+}
+# todo if it has HR data, take it into the account??
+NOT_CARDIO = {
+    'Other',
+}
+
+
+@cdf
+def endomondo_cardio() -> pd.DataFrame:
+    assert len(CARDIO.intersection(NOT_CARDIO)) == 0, (CARDIO, NOT_CARDIO)
+
+    from ..endomondo import dataframe as EDF
+    df = EDF()
+
+    # not sure...
+    # df = df[df['heart_rate_avg'].notna()]
+
+    is_cardio  = df['sport'].isin(CARDIO)
+    not_cardio = df['sport'].isin(NOT_CARDIO)
+    neither    = ~is_cardio & ~not_cardio
+    # if neither -- count, but warn? or show error?
+
+    # todo error about the rest??
+    # todo append errors?
+    df.loc[neither, 'error'] = 'Unexpected exercise type, please mark as cardio or non-cardio'
+    df = df[is_cardio | neither]
+
+    return df
+
+
+def dataframe():
+    return endomondo_cardio()