How to Concatenate Column Values in Pandas DataFrame?

27 July 2024

1

Many times we need to combine values in different columns into a single column. There can be many use cases of this, like combining first and last names of people in a list, combining day, month, and year into a single column of Date, etc. Now we’ll see how we can achieve this with the help of some examples.

Example 1: In this example, we’ll combine two columns of first name last name to a column name. To achieve this we’ll use the map function.

import pandas as pd 
from pandas import DataFrame  
   
# creating a dictionary of names 
Names = {'FirstName':['Suzie','Emily','Mike','Robert'], 
         'LastName':['Bates','Edwards','Curry','Frost']} 
   
# creating a dataframe from dictionary 
df = DataFrame(Names, columns=['FirstName','LastName']) 
print(df) 
   
print('\n') 
   
# concatenating the columns 
df['Name'] = df['FirstName'].map(str) + ' ' + df['LastName'].map(str) 
print(df) 

Output:

Example 2: Similarly, we can concatenate any number of columns in a dataframe. Let’s see through another example to concatenate three different columns of the day, month, and year in a single column Date.

import pandas as pd 
from pandas import DataFrame  
  
# creating a dictionary of Dates 
Dates = {'Day': [1, 29, 23, 4, 15],  
        'Month': ['Aug', 'Feb', 'Aug', 'Apr', 'Mar'],  
        'Year': [1947, 1983, 2007, 2011, 2020]} 
  
# creating a dataframe from dictionary 
df = DataFrame(Dates, columns = ['Day', 'Month', 'Year']) 
print (df) 
  
print('\n') 
  
# concatenating the columns 
df['Date'] = df['Day'].map(str) + '-' + df['Month'].map(str) + '-' + df['Year'].map(str) 
print (df) 

Output:

Example 3:

We can take this process further and concatenate multiple columns from multiple different dataframes. In this example, we combine columns of dataframe df1 and df2 into a single dataframe.

import pandas as pd 
from pandas import DataFrame  
  
# creating a dictionary of Dates 
Dates = {'Day': [1, 1, 1, 1],  
        'Month': ['Jan', 'Jan', 'Jan', 'Jan'],  
        'Year': [2017, 2018, 2019, 2020]}  
  
# creating a dataframe from dictionary 
df1 = DataFrame(Dates, columns = ['Day', 'Month', 'Year'])  
  
# creating a dictionary of Rates 
Rates = {'GDP': [5.8, 7.6, 5.6, 4.1],  
         'Inflation Rate': [2.49, 4.85, 7.66, 6.08]}  
  
# creating a dataframe from dictionary 
df2 = DataFrame(Rates, columns = ['GDP', 'Inflation Rate']) 
  
# combining columns of df1 and df2 
df_combined = df1['Day'].map(str) + '-' + df1['Month'].map(str) + '-' + df1['Year'].map(str) + ': ' + 'GDP: ' + df2['GDP'].map(str) + '; ' + 'Inflation: ' + df2['Inflation Rate'].map(str) 
print (df_combined) 