Answers for "how to merge multiple dataframe based on columns with outer logic"

merge two dataframes based on column

df_outer = pd.merge(df1, df2, on='id', how='outer') #here id is common column

df_outer

Merge multiple dataframs

from functools import reduce

Name of a column in all dataframes is 'DATE'

df_merged = reduce(lambda  left,right: pd.merge(left,right,on=['DATE'],
                                            how='outer'), data_frames)

# if you want to fill the values that don't exist in the lines of merged dataframe simply fill with required strings as

df_merged = reduce(lambda  left,right: pd.merge(left,right,on=['DATE'],
                                            how='outer'), data_frames).fillna('void')