how to connect two different dataframes in pandas code example

Example 1: combining 2 dataframes pandas

df_3 = pd.concat([df_1, df_2])

Example 2: merge dataframe pandas

>>> df1.merge(df2, left_on='lkey', right_on='rkey')
  lkey  value_x rkey  value_y
0  foo        1  foo        5
1  foo        1  foo        8
2  foo        5  foo        5
3  foo        5  foo        8
4  bar        2  bar        6
5  baz        3  baz        7