Renaming Column Names of a data.table in R (2 Examples)
In this post you’ll learn how to assign other names to the columns of a data.table in the R programming language.
Setting up the Examples
First, install and load the data.table package.
install.packages("data.table") # Install & load data.table library("data.table") |
We use the built-in iris data for this post.
data(iris) # Load iris data set head(iris) # Print the head of the data # 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 |
Copy and convert the data to the data.table format.
iris_DT <- data.table::copy(iris) # Replicate iris data set setDT(iris_DT) # Convert iris to a data.table head(iris_DT) # 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 |
Example 1: Rename column “Species”
In this example, we know that there is a column with name Species and we want to edit the column name of the data.table into Type. For that, we first copy the data and use the following lines of code.
iris_DT_2 <- data.table::copy(iris_DT) # Replicate iris data set colnames(iris_DT_2) # Print column names # [1] "Sepal.Length" "Sepal.Width" "Petal.Length" "Petal.Width" "Species" colnames(iris_DT_2)[colnames(iris_DT_2) == "Species"] <- "Type" # Rename column "Species" head(iris_DT_2) # Sepal.Length Sepal.Width Petal.Length Petal.Width Type # 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 |
We successfully renamed the last column.
Example 2: Rename column number three
In Example 2, we rename a column by indexing its position. More precisely, we change the name of column number thee.
iris_DT_3 <- data.table::copy(iris_DT) # Replicate iris data set colnames(iris_DT_3) # Print column names # [1] "Sepal.Length" "Sepal.Width" "Petal.Length" "Petal.Width" "Species" colnames(iris_DT_3)[3] <- "Petal.L" # Rename column number three head(iris_DT_3) # Sepal.Length Sepal.Width Petal.L 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 |
Related Articles
Please find some related tutorials on topics such as dplyr, data conversion, and data.table below:
- Convert data.table Columns to Numeric/Character/Factor
- Error: Can’t rename columns that don’t exist – dplyr & plyr
Note: This article was created in collaboration with Anna-Lena Wölwer. Anna-Lena is a researcher and programmer who creates tutorials on statistical methodology as well as on the R programming language. You may find more info about Anna-Lena and her other articles on her profile page.