Skip to content
Related Articles

Related Articles

How to Do a Left Join in R?

Improve Article
Save Article
  • Last Updated : 21 Dec, 2021
Improve Article
Save Article

In this article, we will discuss how to do a left join in R programming language.

A left join is used to join the table by selecting all the records from the first dataframe and only matching records in the second dataframe.

Method 1: Using merge() function

This function is used to join the dataframes based on the x parameter that specifies left join.

Syntax:

merge(dataframe1,dataframe2, all.x=TRUE)

where,

  • dataframe1 is the first dataframe
  • dataframe2 is the second dataframe

Example: R program to perform two dataframes and perform left join on name column

R




# create first dataframe
data1=data.frame('name'=c('siva','ramu','giri','geetha'),
                 'age'=c(21,23,21,20))
 
# display
print(data1)
 
# create second dataframe
data2=data.frame('name'=c('siva','ramya','giri','geetha','pallavi'),
                 'marks'=c(21,23,21,20,30))
 
# display
print(data2)
 
print("=========================")
 
# left join on name column
print(merge(data1, data2, by='name', all.x=TRUE))


Output:

Method 2: Using left_join

This performs left join on two dataframes which are available in dplyr() package.

Syntax

left_join(df1, df2, by='column_name')

where 

  • df1 and df2 are the two dataframes
  • column_name specifies on which column they are joined

Example: R program to find a let join

R




# load the library
library("dplyr")
 
# create first dataframe
data1=data.frame('name'=c('siva','ramu','giri','geetha'),
                 'age'=c(21,23,21,20))
 
# display
print(data1)
 
# create second dataframe
data2=data.frame('name'=c('siva','ramya','giri','geetha','pallavi'),
                 'marks'=c(21,23,21,20,30))
 
# display
print(data2)
 
print("=========================")
 
# left join on name column
print(left_join(data1, data2, by='name'))


Output:


My Personal Notes arrow_drop_up
Related Articles

Start Your Coding Journey Now!