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")
df1.merge(df2, how='left', on='a')
pd.merge(product,customer,left_on='Product_name',right_on='Purchased_Product')
pd.merge(product,customer,how='inner',left_on=['Product_ID','Seller_City'],right_on=['Product_ID','City'])