R Set Row & Column Names of Data with Unknown Dimension (Example)
In this article you’ll learn how to change row and column names of a data frame or matrix without knowing the dimensions in the R programming language.
The post consists of this information:
Let’s dive into it:
Creation of Example Data
The first step is to create some example data:
data <- matrix(1:20, ncol = 5) # Create example matrix data # Print example matrix
Table 1 shows the structure of the example data – It is made up of four observations and five columns. However, let’s assume that we don’t know these numbers of rows and columns.
Example 1: Set Row Names of Data without Knowing the Number of Rows
The following R code illustrates how to set the row numbers of a matrix from 1 to the number of rows without actually knowing the number of rows.
For this, we can use the rownames and nrow functions as shown below:
rownames(data) <- 1:nrow(data) # Set row names data # Print updated data
As shown in Table 2, we have set the row names of our matrix by executing the previously shown R programming syntax.
The column names are still not specified though…
Example 2: Set Column Names of Data without Knowing the Number of Columns
The syntax below explains how to define variable names of an unknown number of columns.
colnames(data) <- paste0("Col", 1:ncol(data)) # Set column names data # Print updated data
As shown in Table 3, the previously shown R syntax has created a matrix with manually specified column names even though we didn’t explicitly specify the dimensions of our data.
Video, Further Resources & Summary
I have recently published a video instruction on my YouTube channel, which explains the contents of this tutorial. You can find the video below:
Furthermore, you might read the other articles on this homepage.
- Convert Row Names into Column of Data Frame
- Assign Column Names Based On Existing Row
- Export CSV File without Row Names in R
- Extract Values from Matrix by Column & Row Names
- Convert Values in Column into Row Names of Data Frame
- R Programming Overview
On this page you have learned how to set row and column names without knowing the number of rows and columns in R programming.
In this tutorial, we have changed the row and column names of a matrix object. However, please note that we could apply the same syntax to a data frame object as well.
Let me know in the comments, in case you have any further questions.