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Add a new column to existing DataFrame using Dataframe.assign()

Learn, how to Add a new column to existing DataFrame using Dataframe.assign()? By IncludeHelp Last updated : April 10, 2023

DataFrame.assign() Method

We have already discussed how to add a column in the existing DataFrame using List as a column? and adding a column by using DataFrame.insert() method. We can also add a column by using DataFrame.assign() method, which is used to assign new columns to a DataFrame and returns a new object having the new column also. Existing columns that are re-assigned will be overwritten.

Syntax

DataFrame.assign(**kwargs)

Python program to add a new column to existing DataFrame using Dataframe.assign()

# Importing pandas package 
import pandas as pd 
   
# Dictionary having students data
students = {'Name':['Alvin', 'Alex', 'Peter'],
'Age':[21, 22, 19]} 
   
# Convert the dictionary into DataFrame  
dataframe = pd.DataFrame(students) 

# Print the data before adding column
print("Data before adding column...")
print(dataframe)
print()

# Add a column course using DataFrame.insert()
dataframe1 = dataframe.assign(Course = ['B.Tech', 'MCA', 'B.E.'])
 
# Print the data after adding column
print("Data after adding column (new/updated DataFrame)...")
print(dataframe1)
print()

Output:

Data before adding column...
    Name  Age
0  Alvin   21
1   Alex   22
2  Peter   19

Data after adding column (new/updated DataFrame)...
    Name  Age  Course
0  Alvin   21  B.Tech
1   Alex   22     MCA
2  Peter   19    B.E.

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