Pandas DataFrame insert() Method

In this tutorial, we will learn the Python pandas DataFrame.insert() method. This method inserts the column into DataFrame at the specified location. It raises a ValueError if the column is already contained in the DataFrame unless allow_duplicates is set to True.

The below shows the syntax of the DataFrame.insert() method.

Syntax

DataFrame.insert(loc, column, value, allow_duplicates=False)

Parameters

loc: int. Insertion index. Must verify 0 <= loc <= len(columns).

column: str, number, or hashable object. Label of the inserted column.

value: int, Series, or array-like

allow_duplicates: bool, optional

Example 1: Inserting new column into the DataFrame

We can insert a new column to the DataFrame using the DataFrame.insert() method. See, how it works in the below example.

#importing pandas as pd
import pandas as pd
df=pd.DataFrame({'A':[1,2,3,4],'B':[5,6,7,8]})
print("The DataFrame is")
print(df)
print("Adding column to the DataFrame")
df.insert(2,'C',1)
print(df)

Once we run the program we will get the following output.

The DataFrame is
A B
0 1 5
1 2 6
2 3 7
3 4 8
Adding column to the DataFrame
A B C
0 1 5 1
1 2 6 1
2 3 7 1
3 4 8 1

Example 2: Inserting new column into the DataFrame

We can insert a Series as column of the DataFrame using the DataFrame.insert() method. It will return a new dataframe after adding the column.

#importing pandas as pd
import pandas as pd
df=pd.DataFrame({'A':[1,2,3,4],'B':[5,6,7,8]})
print("The DataFrame is")
print(df)
print("Adding column to the DataFrame")
df.insert(0,'C',1)
print(df)

Once we run the program we will get the following output.

The DataFrame is
A B
0 1 5
1 2 6
2 3 7
3 4 8
Adding column to the DataFrame
C A B
0 1 1 5
1 1 2 6
2 1 3 7
3 1 4 8

Example : Error while inserting the column to the DataFrame

The DataFrame.insert() method raises a ValueError, if the column is already contained in the DataFrame.

#importing pandas as pd
import pandas as pd
df=pd.DataFrame({'A':[1,2,3,4],'B':[5,6,7,8]})
print("Adding column to the DataFrame")
df.insert(2,'A',1)
print(df)

Once we run the program we will get the following output.

ValueError: cannot insert A, already exists

Conclusion

In this tutorial, we learned the Python pandas DataFrame.insert() method. We learned the syntax and applying this method in the examples.