Pandas se unió
df.merge(df2, left_on = "doc_id", right_on = "doc_num", how = "left")
Comfortable Cockroach
df.merge(df2, left_on = "doc_id", right_on = "doc_num", how = "left")df_outer = pd.merge(df1, df2, on='id', how='outer') #here id is common column
df_outer
df_3 = pd.concat([df_1, df_2])
df['FullName'] = df[['First_Name', 'Last_Name']].agg('-'.join, axis=1)# df1 as main df and use the feild from df2 and map it into df1
df1.merge(df2,on='columnName',how='left')df = df1.append(df2)