str_match & str_match_all Functions in R (2 Examples)
In this tutorial you’ll learn how to apply str_match and str_match_all to extract matched groups from a string in R.
The tutorial contains this information:
- Creation of Example Data
- Example 1: Application of str_match Function in R
- Example 2: Application of str_match_all Function in R
- Video & Further Resources
So now the part you have been waiting for – the examples…
Creation of Example Data
Before we can apply the str_match and str_match_all functions, we need to create a character string in R:
x <- c("my example string") # Create character string
install.packages("stringr") # Install stringr package library("stringr") # Load stringr package
Example 1: Application of str_match Function in R
In Example 1, I’ll show you how to apply the str_match function. First, we will check whether the letter “m” is contained in our example character string x:
str_match(x, "m") # Apply str_match function # [,1] # [1,] "m"
The str_match function is returning a matrix, which contains the value “m”. In other words, yes there was a match!
Let’s see what happens when we check for a different pattern:
str_match(x, "yyy") # Apply str_match function # [,1] # [1,] NA
As you can see, the str_match command returns a matrix containing an NA value. The pattern “yyy” is not existing in our character string.
Example 2: Application of str_match_all Function in R
The str_match command of Example 1 returns only the first matching pattern. However, with the str_match_all function we can return all matching pattern in a matrix:
str_match_all(x, "m") # Apply str_match_all function # [] # [,1] # [1,] "m" # [2,] "m"
The letter “m” occurs twice in our example string.
Video & Further Resources
Do you want to learn more about the handling of strings in R? Then you could have a look at the following video of my YouTube channel. In the video, I’m explaining the R programming syntax of this tutorial in a live session:
The YouTube video will be added soon.
Furthermore, I can recommend to read the other articles of statisticsglobe.com. I have released numerous other articles already.
You learned in this tutorial how to return matched groups from a character string in the R programming language. In case you have any additional questions, let me know in the comments below.
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