join two data frames in a particular series code example

Example 1: union df pandas

pd.concat([df1, df2])

Example 2: How to join two dataframes by 2 columns so they have only the common rows?

import pandas as pd 
import numpy as np

df1 = pd.DataFrame({'fruit': ['apple', 'banana', 'orange'] * 3,
                    'weight': ['high', 'medium', 'low'] * 3,
                    'price': np.random.randint(0, 15, 9)})

df2 = pd.DataFrame({'pazham': ['apple', 'orange', 'pine'] * 2,
                    'kilo': ['high', 'low'] * 3,
                    'price': np.random.randint(0, 15, 6)})
out = df1.merge(df2,left_on=('fruit','weight'),right_on=('pazham','kilo'),how='inner',suffixes=('_left','_right')).head(10)