pandas join on column value code 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 left join

df.merge(df2, left_on = "doc_id", right_on = "doc_num", how = "left")