Select variables (columns) in R using Dplyr
Last Updated :
21 Jul, 2021
In this article, we are going to select variables or columns in R programming language using dplyr library.
Dataset in use:
Select column with column name
Here we will use select() method to select column by its name
Syntax:
select(dataframe,column1,column2,.,column n)
Here, data frame is the input dataframe and columns are the columns in the dataframe to be displayed
Example 1: R program to select columns
R
# load the library
library(dplyr)
# create dataframe with 3 columns
# id,name and address
data1=data.frame(id=c(1,2,3,4,5,6,7,1,4,2),
name=c('sravan','ojaswi','bobby','gnanesh',
'rohith','pinkey','dhanush',
'sravan','gnanesh','ojaswi'),
address=c('hyd','hyd','ponnur','tenali',
'vijayawada','vijayawada',
'guntur','hyd','tenali','hyd'))
# select id column from the dataframe by
# column name
print(select(data1,id))
# select name column from the dataframe by
# column name
print(select(data1,name))
Output:
Example 2: R program to select multiple columns
R
# load the library
library(dplyr)
# create dataframe with 3 columns
# id,name and address
data1=data.frame(id=c(1,2,3,4,5,6,7,1,4,2),
name=c('sravan','ojaswi','bobby','gnanesh',
'rohith','pinkey','dhanush',
'sravan','gnanesh','ojaswi'),
address=c('hyd','hyd','ponnur','tenali',
'vijayawada','vijayawada',
'guntur','hyd','tenali','hyd'))
# select multiple columns from the dataframe
# by column name
print(select(data1,id,name,address))
Output:
Select column(s) by position
We can also use the column position and get the column using select() method. Position starts with 1.
Syntax:
select(dataframe,column1_position,column2_position,.,column n_position)
where, dataframe is the input dataframe and column position is an column number
For selecting multiple columns we can use range operator ";" to select columns by their position
Syntax:
select(dataframe,start_position:end_position)
where, dataframe is the input dataframe, start_position  is a column number starting position and end_position  is a column number ending position
Example 1: R program to select particular column by column position
R
# load the library
library(dplyr)
# create dataframe with 3 columns
# id,name and address
data1=data.frame(id=c(1,2,3,4,5,6,7,1,4,2),
name=c('sravan','ojaswi','bobby','gnanesh',
'rohith','pinkey','dhanush',
'sravan','gnanesh','ojaswi'),
address=c('hyd','hyd','ponnur','tenali',
'vijayawada','vijayawada',
'guntur','hyd','tenali','hyd'))
# select first column by column position
print(select(data1,1))
# select third column by column position
print(select(data1,3))
Output:
Example 2: R program to select multiple columns by positions
R
# load the library
library(dplyr)
# create dataframe with 3 columns
# id,name and address
data1=data.frame(id=c(1,2,3,4,5,6,7,1,4,2),
name=c('sravan','ojaswi','bobby','gnanesh',
'rohith','pinkey','dhanush','sravan',
'gnanesh','ojaswi'),
address=c('hyd','hyd','ponnur','tenali',
'vijayawada','vijayawada','guntur',
'hyd','tenali','hyd'))
# select multiple column by column position
print(select(data1,1,2))
Output:
Example 3: R program to select multiple columns by position with range operator
R
# load the library
library(dplyr)
# create dataframe with 3 columns
# id,name and address
data1=data.frame(id=c(1,2,3,4,5,6,7,1,4,2),
name=c('sravan','ojaswi','bobby','gnanesh',
'rohith','pinkey','dhanush','sravan',
'gnanesh','ojaswi'),
address=c('hyd','hyd','ponnur','tenali',
'vijayawada','vijayawada','guntur',
'hyd','tenali','hyd'))
# select multiple column by column
# position with : operator
print(select(data1,1:3))
Output:
Select column which contains a value or matches a pattern
Here, we will display the column values based on values or pattern present in the columnÂ
Method 1: Using contains()Â
Display the column that contains the given sub string
Syntax:
select(dataframe,contains('sub_string'))
Here, dataframe is the input dataframe and sub_string is the string present in the column name
Example: R program to select column based on substring
R
# load the library
library(dplyr)
# create dataframe with 3 columns
# id,name and address
data1=data.frame(id=c(1,2,3,4,5,6,7,1,4,2),
name=c('sravan','ojaswi','bobby','gnanesh',
'rohith','pinkey','dhanush','sravan',
'gnanesh','ojaswi'),
address=c('hyd','hyd','ponnur','tenali',
'vijayawada','vijayawada','guntur',
'hyd','tenali','hyd'))
# select column that contains am
print(select(data1,contains('am')))
# select column that contains d
print(select(data1,contains('d')))
# select column that contains dd
print(select(data1,contains('dd')))
Output:
Method 2: Using matches()
It will check and display the column that contains the given sub string
select(dataframe,matches('sub_string'))
Here, dataframe is the input dataframe and sub_string is the string present in the column name
Example: R program to select column based on substring
R
# load the library
library(dplyr)
# create dataframe with 3 columns
# id,name and address
data1=data.frame(id=c(1,2,3,4,5,6,7,1,4,2),
name=c('sravan','ojaswi','bobby','gnanesh',
'rohith','pinkey','dhanush','sravan',
'gnanesh','ojaswi'),
address=c('hyd','hyd','ponnur','tenali',
'vijayawada','vijayawada','guntur',
'hyd','tenali','hyd'))
# select column that matches with am
print(select(data1,matches('am')))
# select column that matches with d
print(select(data1,matches ('d')))
# select column that matches with dd
print(select(data1,matches ('dd')))
Output:
Select column which starts with or ends with certain character
Here we can also select columns based on starting and ending characters.
- starts_with() is used to return the column that starts with the given character.
Syntax:
select(dataframe,starts_with('substring'))
Where, dataframe is the input dataframe and substring is the character/string that starts with it
- ends_with() is used to return the column that ends with the given character.
Syntax:
select(dataframe,ends_with('substring'))
where, dataframe is the input dataframe and substring is the character/string that ends with it
Example 1: R program to display columns that starts with a character/substring
R
# load the library
library(dplyr)
# create dataframe with 3 columns id,name and address
data1=data.frame(id=c(1,2,3,4,5,6,7,1,4,2),
name=c('sravan','ojaswi','bobby','gnanesh',
'rohith','pinkey','dhanush','sravan',
'gnanesh','ojaswi'),
address=c('hyd','hyd','ponnur','tenali',
'vijayawada','vijayawada','guntur',
'hyd','tenali','hyd'))
# select column that starts with n
print(select(data1,starts_with('n')))
# select column that starts with add
print(select(data1,starts_with('add')))
Output:
Example 2: R program to select column that ends with a given string or character
R
# load the library
library(dplyr)
# create dataframe with 3 columns id,name and address
data1=data.frame(id=c(1,2,3,4,5,6,7,1,4,2),
name=c('sravan','ojaswi','bobby','gnanesh',
'rohith','pinkey','dhanush','sravan',
'gnanesh','ojaswi'),
address=c('hyd','hyd','ponnur','tenali','vijayawada',
'vijayawada','guntur','hyd','tenali','hyd'))
# select column that ends with ss
print(select(data1,ends_with('ss')))
# select column that ends with d
print(select(data1,ends_with('d')))
Output:
Select all columns
We can select all the columns in the data frame by using everything() method.
Syntax:
select(dataframe,everything())
Example: R program to select all columns
R
# load the library
library(dplyr)
# create dataframe with 3 columns
# id,name and address
data1=data.frame(id=c(1,2,3,4,5,6,7,1,4,2),
name=c('sravan','ojaswi','bobby','gnanesh',
'rohith','pinkey','dhanush','sravan',
'gnanesh','ojaswi'),
address=c('hyd','hyd','ponnur','tenali',
'vijayawada','vijayawada','guntur',
'hyd','tenali','hyd'))
# select all columns using everything method
print(select(data1,everything()))
Output:
