How to find the common elements in a Pandas DataFrame?

To find the common elements in a Pandas DataFrame, we can use the merge() method with a list of columns

Steps

• Create a two-dimensional, size-mutable, potentially heterogeneous tabular data, df1.

• Print the input DataFrame, df1.

• Create another two-dimensional tabular data, df2.

• Print the input DataFrame, df2.

• Find the common elements using merge() method.

• Print the common DataFrame.

Example

import pandas as pd
df1 = pd.DataFrame(
   {
      "x": [5, 2, 7, 0],
      "y": [4, 7, 5, 1],
      "z": [9, 3, 5, 1]
   }
)
df2 = pd.DataFrame(
   {
      "x": [5, 2, 7, 0, 11, 12],
      "y": [4, 7, 5, 1, 19, 20],
      "z": [9, 3, 5, 1, 29, 30]
   }
)
print("Input DataFrame 1 is:\n", df1)
print("Input DataFrame 2 is:\n", df2)
common = df1.merge(df2, on=['x', 'y', 'z'])
print("Common of DataFrame 1 and 2 is: \n", common)

Output

Input DataFrame 1 is:
   x  y  z
0  5  4  9
1  2  7  3
2  7  5  5
3  0  1  1

Input DataFrame 2 is:
   x  y  z
0  5  4  9
1  2  7  3
2  7  5  5
3  0  1  1
4 11 19 29
5 12 20 30
Common of DataFrame 1 and 2 is:
   x  y z
0  5  4 9
1  2 7 3
2  7 5 5
3  0 1 1