pandas outer merge example

Example 1: pd merge on multiple columns

new_df = pd.merge(A_df, B_df,  how='left', left_on=['A_c1','c2'], right_on = ['B_c1','c2'])

Example 2: pandas merge python

import pandas as pd
df1 = pd.DataFrame({'lkey': ['foo', 'bar', 'baz', 'foo'],
                    'value': [1, 2, 3, 5]})
df2 = pd.DataFrame({'rkey': ['foo', 'bar', 'baz', 'foo'],
                    'value': [5, 6, 7, 8]})
df1.merge(df2, left_on='lkey', right_on='rkey')

Example 3: python merge using or statement

suff_A = ['_on_A_match_1', '_on_A_match_2']
suff_B = ['_on_B_match_1', '_on_B_match_2']

pd.concat([df1.merge(df2, on='A', suffixes=suff_A), 
           df1.merge(df2, on='B', suffixes=suff_B)])

     A  A_on_B_match_1  A_on_B_match_2    B  B_on_A_match_1  B_on_A_match_2
0  1.0             NaN             NaN  NaN             9.0             4.0
1  4.0             NaN             NaN  NaN             5.0             5.0
0  NaN             2.0             6.0  8.0             NaN             NaN
1  NaN             4.0             4.0  5.0             NaN             NaN