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Remove duplicate rows based on multiple columns using Dplyr in R

  • Last Updated : 28 Jul, 2021

In this article, we will learn how to remove duplicate rows based on multiple columns using dplyr in R programming language.

Dataframe in use:

            lang value usage
1        Java    21    21
2           C    21    21
3      Python     3     0
4          GO     5    99
5        RUST   180    44
6  Javascript     9    48
7         Cpp    12    53
8        Java    21    21
9       Julia     6     6
10 Typescript     0     8
11     Python     3     0
12         GO     6     6

Removing duplicate rows based on the Single Column

distinct() function can be used to filter out the duplicate rows. We just have to pass our R object and the column name as an argument in the distinct() function. 

Note: We have used this parameter “.keep_all= TRUE” in the function because by default its FALSE, and it will print only the distinct values of the specified column, but we want all the columns so we have to make it TRUE, such that it will print all the other columns along with the current column. 

Syntax: distinct(df, column_name, .keep_all= TRUE)



Parameters:

df: dataframe object

column_name: column name based on which duplicate rows will be removed

Example: R program to remove duplicate rows based on single column

R




library(dplyr)
  
df <- data.frame (lang =c ('Java','C','Python','GO','RUST','Javascript',
                      'Cpp','Java','Julia','Typescript','Python','GO'),
  
                      value = c (21,21,3,5,180,9,12,21,6,0,3,6),
  
                      usage =c(21,21,0,99,44,48,53,21,6,8,0,6))
  
distinct(df, lang, .keep_all= TRUE)

Output:

lang value usage
1       Java    21    21
2          C    21    21
3     Python     3     0
4         GO     5    99
5       RUST   180    44
6 Javascript     9    48
7        Cpp    12    53
8      Julia     6     6
9 Typescript     0     8

 Removing duplicate rows based on Multiple columns

We can remove duplicate values on the basis of ‘value & usage‘ columns, bypassing those column names as an argument in the distinct function. 

Syntax: distinct(df, col1,col2, .keep_all= TRUE)



Parameters:

df: dataframe object

col1,col2: column name based on which duplicate rows will be removed

Example: R program to remove duplicate rows based on multiple columns 

R




library(dplyr)
  
df <- data.frame (lang =c ('Java','C','Python','GO','RUST','Javascript',
                      'Cpp','Java','Julia','Typescript','Python','GO'),
  
                      value = c (21,21,3,5,180,9,12,21,6,0,3,6),
  
                      usage =c(21,21,0,99,44,48,53,21,6,8,0,6))
  
distinct(df, value, usage, .keep_all= TRUE)

Output:

        lang value usage
1       Java    21    21
2     Python     3     0
3         GO     5    99
4       RUST   180    44
5 Javascript     9    48
6        Cpp    12    53
7      Julia     6     6
8 Typescript     0     8

Remove all the duplicate rows from the dataframe

In this case, we just have to pass the entire dataframe as an argument in distinct() function, it then checks for all the duplicate rows for all variables/columns and removes them. 

Syntax: distinct(df)

Parameters:

df: dataframe object



Example: R program to remove all the duplicate rows from the database

R




library(dplyr)
  
df <- data.frame (lang =c ('Java','C','Python','GO','RUST','Javascript',
                      'Cpp','Java','Julia','Typescript','Python','GO'),
  
                      value = c (21,21,3,5,180,9,12,21,6,0,3,6),
  
                      usage =c(21,21,0,99,44,48,53,21,6,8,0,6))
  
distinct(df)

Output:

lang value usage
1        Java    21    21
2           C    21    21
3      Python     3     0
4          GO     5    99
5        RUST   180    44
6  Javascript     9    48
7         Cpp    12    53
8       Julia     6     6
9  Typescript     0     8
10         GO     6     6

Using duplicated() function

In this approach, we have used duplicated() to remove all the duplicate rows, here duplicated function is used to check for the duplicate rows, then the column names/variables are passed in the duplicated function. 

Note: We have used the NOT(!) operator because we want to filter out or remove the duplicate rows since the duplicated function provides the duplicate rows we negate them using ‘!‘ operator.

Syntax:

df %>%

  filter(!duplicated(cbind(col1,  col2,..)))

Parameters:

col1,col2: Pass the names of columns based on which you want to remove duplicated values

cbind():It is used to bind together column names such that multiple column names can be used for filtering

duplicated(): returns the duplicate rows

Example: R program to remove duplicate using duplicate() 

R




library(dplyr)
  
df <- data.frame (lang =c ('Java','C','Python','GO','RUST','Javascript',
                      'Cpp','Java','Julia','Typescript','Python','GO'),
  
                      value = c (21,21,3,5,180,9,12,21,6,0,3,6),
  
                      usage =c(21,21,0,99,44,48,53,21,6,8,0,6))
  
df %>%
  filter(!duplicated(cbind(value, usage)))

Output:

        lang value usage
1       Java    21    21
2     Python     3     0
3         GO     5    99
4       RUST   180    44
5 Javascript     9    48
6        Cpp    12    53
7      Julia     6     6
8 Typescript     0     8



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