Mutate function in R

In this article we will discuss how we Add new Variables to a Data Frame using Existing Variables in R Programming Language using mutate() Function in R.

mutate() Function in R

mutate() function in R Programming Language is used to add new variables in a data frame which are formed by performing operations on existing variables.

Syntax:

mutate(x, expr)

Parameters:

x: Data Frame

expr: operation on variables

Types of mutate() Function in R

In R there are five types of main function for mutate that are discribe as below. we will use dplyr package in R for all mutate functions.

• mutate()
• transmute() 
• mutate_all()
• mutate_at()
• mutate_if()

mutate() Function in R

R

# R program to add new variables
# in a data frame

# 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") )

# Calculating a variable x3 which is sum of height
# and age printing with ht and age
mutate(d, x3 = ht + age)

Output:

     name age ht school x3
1    Abhi   7 46    yes 53
2 Bhavesh   5 NA    yes NA
3  Chaman   9 NA     no NA
4   Dimri  16 69     no 85

transmute() Function in R

The transmute() function in R is used to create new variables or modify existing variables in a data frame, while simultaneously dropping the variables that are not part of the result.

R

# Load the dplyr package
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")
)

# Use transmute to create a new variable 'age_in_months' and drop the 'age' variable
result <- transmute(d,
                    name = name,
                    age_in_months = age * 12,
                    ht,
                    school)

# Print the resulting data frame
print(result)

Output:

     name age_in_months ht school
1    Abhi            84 46    yes
2 Bhavesh            60 NA    yes
3  Chaman           108 NA     no
4   Dimri           192 69     no

mutate_all() Function in R

The mutate_all() function is used to apply a transformation to all variables in a data frame simultaneously.

R

# Load the dplyr package
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")
)

# Example: Double all numeric variables
d_mutate_all <- d %>%
  mutate_all(~ ifelse(is.numeric(.), . * 2, .))

print(d_mutate_all)

Output:

  name age ht school
1 Abhi  14 92    yes
2 Abhi  14 92    yes
3 Abhi  14 92    yes
4 Abhi  14 92    yes

mutate_at() Function in R

R

# Load the dplyr package
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")
)

# Example: Square only the 'age' variable
d_mutate_at <- d %>%
  mutate_at(vars(age), ~ .^2)

print(d_mutate_at)

Output:

     name age ht school
1    Abhi  49 46    yes
2 Bhavesh  25 NA    yes
3  Chaman  81 NA     no
4   Dimri 256 69     no

mutate_if() Function in R

The mutate_if() function in R, part of the dplyr package, is used to apply a transformation to variables in a data frame based on a specific condition. It allows you to selectively apply a mutation only to the variables that satisfy the specified condition.

R

# Load the dplyr package
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")
)

# Use mutate_if to double the values of numeric variables
d_mutate_if <- d %>%
  mutate_if(is.numeric, ~ . * 2)

# Print the resulting data frame
print(d_mutate_if)

Output:

     name age  ht school
1    Abhi  14  92    yes
2 Bhavesh  10  NA    yes
3  Chaman  18  NA     no
4   Dimri  32 138     no

mutate() function in R is an essential function in the data manipulation toolkit of R, providing a clean and efficient way to modify and enhance data frames.