How to use mapvalues() method In R Language

Method 2: Using revalue() method

The mapvalues() method in the plyr package in R is used to replace the specified values with new values, in the factor vector. The changes are not retained in the original vector.

Syntax: mapvalues(x, from, to)

Arguments :

x – the factor vector to modify

from – a vector of the items to replace

to – a vector of replacement values

R

# importing req libraries 
library("plyr") 
  
# declare a factor  
val <- factor(c("Geeks","For","Geeks", 
                "Coding","Fun")) 
  
# printing the levels of factor variables 
print("Levels of factor") 
lvls <- levels(val) 
print(lvls) 
  
# renaming the factors 
mapvalues(val, from = c("Fun","Coding"), 
          to = c("Learning", "Programming")) 
print("Modified Levels of factor") 
print(levels(val)) 

Output:

[1] "Levels of factor"
[1] "Coding" "For"    "Fun"    "Geeks"  
Geeks For Geeks Programming Learning
Levels:
[1] "Modified Levels of factor"
[1] "Coding" "For"    "Fun"    "Geeks"

How to Rename Factor Levels in R?

In this article, we are going to how to rename factor levels in R programming language.

A factor variable in R is represented using categorical variables which are represented using various levels. Each unique value is represented using a unique level value. A factor variable or vector in R can be declared using the factor() method.

Syntax: factor(vec)

Arguments : vec – The vector

The unique levels of the factor can be extracted using the levels() method which takes as argument the factor vector created. It displays all the unique entries within the factor variable.