Rename Data Frame Columns

Last updated on Jul 23, 2022 3 min read R

There are several ways of renaming variables in R. In this post you will learn how to change a column name using base R function, the dplyr way and using data.table package.

I will use the R built-in iris data frame.

head(iris)
##   Sepal.Length Sepal.Width Petal.Length Petal.Width Species
## 1          5.1         3.5          1.4         0.2  setosa
## 2          4.9         3.0          1.4         0.2  setosa
## 3          4.7         3.2          1.3         0.2  setosa
## 4          4.6         3.1          1.5         0.2  setosa
## 5          5.0         3.6          1.4         0.2  setosa
## 6          5.4         3.9          1.7         0.4  setosa

Rename column names with R base functions

Let’s change Sepal.Length to S.P. The procedure is simple; get column names using names() or colnames, extract the specific column name, and assign a new name.

colnames(iris)[colnames(iris)=="Sepal.Length"] <- "S.P"
head(iris)
##   S.P Sepal.Width Petal.Length Petal.Width Species
## 1 5.1         3.5          1.4         0.2  setosa
## 2 4.9         3.0          1.4         0.2  setosa
## 3 4.7         3.2          1.3         0.2  setosa
## 4 4.6         3.1          1.5         0.2  setosa
## 5 5.0         3.6          1.4         0.2  setosa
## 6 5.4         3.9          1.7         0.4  setosa

The code does the following:

  1. colnames(iris) looks into all the names in the iris.
  2. names(iris) == "Sepal.Length" returns a vector with true and false values to extract the variable name you want to change.
  3. <- "S.P" assigns the new name.

You can also rename a variable by its index as well. For example, let’s change Sepal.Width [the second column] to S.W.

colnames(iris)[2] <- "S.W"
head(iris)
##   S.P S.W Petal.Length Petal.Width Species
## 1 5.1 3.5          1.4         0.2  setosa
## 2 4.9 3.0          1.4         0.2  setosa
## 3 4.7 3.2          1.3         0.2  setosa
## 4 4.6 3.1          1.5         0.2  setosa
## 5 5.0 3.6          1.4         0.2  setosa
## 6 5.4 3.9          1.7         0.4  setosa

Rename column names with dplyr

You can use rename() function to change column names as following. For instance, let’s change Petal.Length to P.L and Petal.Width to P.W.

# install.packages("dplyr")
library(dplyr)
## Warning: package 'dplyr' was built under R version 4.0.5
iris %>%
  rename(
    P.L = Petal.Length,
    P.W = Petal.Width
  ) %>%
  head()
##   S.P S.W P.L P.W Species
## 1 5.1 3.5 1.4 0.2  setosa
## 2 4.9 3.0 1.4 0.2  setosa
## 3 4.7 3.2 1.3 0.2  setosa
## 4 4.6 3.1 1.5 0.2  setosa
## 5 5.0 3.6 1.4 0.2  setosa
## 6 5.4 3.9 1.7 0.4  setosa

Rename column names with data.table

setnames() function from data.table package can be used to rename a variable. The syntax is setnames(df, "old_name", "new_name"). As an example, let’s change Species to SPECIES.

# install.packages("data.table")
library(data.table)
setnames(iris,
         "Species", "SPECIES")
colnames(iris)
## [1] "Sepal.Length" "Sepal.Width"  "Petal.Length" "Petal.Width"  "SPECIES"
R
Fahim Ahmad
Fahim Ahmad

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