Avoiding pandas copywithsetting error

avoid_copywithsetting_error.py

#SettingWithCopyWarning: 
#A value is trying to be set on a copy of a slice from a DataFrame.
#Try using .loc[row_indexer,col_indexer] = value instead

# assign was introduced in pandas 0.16 to deal with this false positive

# Instead of 
df_weekly_season.loc[:, 'market'] = market 
# or
df_weekly_season['market'] = market
# do 
df_weekly_season = df_weekly_season.assign(market=market)

# Instead of 
df_weekly_season['DOW_ENG'] = weekly_season['ds'].apply(
     lambda x: calendar.day_name[pd.to_datetime(x).weekday()])
# do
df_weekly_season = df_weekly_season.assign(DOW_ENG=weekly_season['ds'].apply(
    lambda x: calendar.day_name[pd.to_datetime(x).weekday()]))