code: def add_cyclic_datepart(df:DataFrame, field_name:str, prefix:str=None, drop:bool=True, time:bool=False, add_linear:bool=False):
      "Helper function that adds trigonometric date/time features to a date in the column `field_name` of `df`."
      make_date(df, field_name)
      field = df[field_name]
      prefix = ifnone(prefix, re.sub('[Dd]ate$', '', field_name))
      series = field.apply(partial(cyclic_dt_features, time=time, add_linear=add_linear))
      columns = [prefix + c for c in cyclic_dt_feat_names(time, add_linear)]
      df_feats = pd.DataFrame([item for item in series], columns=columns, index=series.index)
      df = pd.concat([df, df_feats], axis=1)
      if drop: df.drop(field_name, axis=1, inplace=True)
      return df add_cyclic_datepart(df:DataFrame, field_name:str, prefix:str=None, drop:bool=True, time:bool=False, add_linear:bool=False):
      "Helper function that adds trigonometric date/time features to a date in the column `field_name` of `df`."
      make_date(df, field_name)
      field = df[field_name]
      prefix = ifnone(prefix, re.sub('[Dd]ate$', '', field_name))
      series = field.apply(partial(cyclic_dt_features, time=time, add_linear=add_linear))
      columns = [prefix + c for c in cyclic_dt_feat_names(time, add_linear)]
      df_feats = pd.DataFrame([item for item in series], columns=columns, index=series.index)
      df = pd.concat([df, df_feats], axis=1)
      if drop: df.drop(field_name, axis=1, inplace=True)
      return df
docs: Helper function that adds trigonometric date/time features to a date in the column `field_name` of `df`.