Merge


Merge
Merge by Index
pd.merge(train_1, train_2, left_index=True, right_index=True)
Merge by a Column
 pd.merge(left=train_1, right=train_2, how='left', on=['column'])
Merge by Columns
 pd.merge(left=train_1, right=train_2, how='left', on=['column_1', 'column_2'])