Choose Specific Columns of a Data Frame in R Programming – select() Function

select() function in R Language is used to choose whether a column of the data frame is selected or not.

Syntax: select(x, expr)

Parameters:
x: Data frame
expr: condition for selection

Example 1:

# R program to select specific columns

# Loading library
library(dplyr)

# Create a data frame
d <- data.frame( name = c("Abhi", "Bhavesh", "Chaman", "Dimri"),
                 age = c(7, 5, 9, 16),
                 ht = c(46, NA, NA, 69),
                 school = c("yes", "yes", "no", "no") )

# startswith() function to print only ht data
select(d, starts_with("ht"))

# -startswith() function to
# print everything except ht data
select(d, -starts_with("ht"))

Output:

  ht
1 46
2 NA
3 NA
4 69
     name age school
1    Abhi   7    yes
2 Bhavesh   5    yes
3  Chaman   9     no
4   Dimri  16     no

Example 2:

# R program to select specific columns

# Loading library
library(dplyr)

# Create a data frame
d <- data.frame( name = c("Abhi", "Bhavesh", "Chaman", "Dimri"),
                 age = c(7, 5, 9, 16),
                 ht = c(46, NA, NA, 69),
                 school = c("yes", "yes", "no", "no") )

# Printing column 1 to 2
select(d, 1:2)

# Printing data of column heading containing 'a'
select(d, contains("a"))

# Printing data of column heading which matches 'na'
select(d, matches("na"))

Output:

     name age
1    Abhi   7
2 Bhavesh   5
3  Chaman   9
4   Dimri  16
     name age
1    Abhi   7
2 Bhavesh   5
3  Chaman   9
4   Dimri  16
     name
1    Abhi
2 Bhavesh
3  Chaman
4   Dimri