Table of Contents
str_count() is a string manipulation function in R that counts the number of matching patterns in a string. It takes two parameters: the string to search and the pattern to search for. The function returns the number of times the pattern is found in the string. str_count() can be used to count the number of occurrences of a word, phrase, or character in a string. Examples of using str_count() include counting the number of vowels in a string, counting the number of words in a sentence, and counting the number of times a number appears in a list.
The str_count() function from the package in R can be used to count the number of matches in a string.
This function uses the following syntax:
str_count(string, pattern = “”)
where:
- string: Character vector
- pattern: Pattern to look for
The following examples show how to use this function in practice
Example 1: Use str_count with One Pattern
The following code shows how to use the str_count() function to count the number of times the letter ‘a’ occurs in each element in a character vector:
library(stringr)
#create character vector
x <- c('Mavs', 'Cavs', 'Nets', 'Trailblazers', 'Heat')
#count number of times 'a' occurs in each element in vector
str_count(x, 'a')
[1] 1 1 0 2 1
Here’s how to interpret the output:
- The pattern ‘a’ occurs 1 time in ‘Mavs’
- The pattern ‘a’ occurs 1 time in ‘Cavs’
- The pattern ‘a’ occurs 0 times in ‘Nets’
And so on.
Note that str_count() is also case-sensitive, so a capital ‘A’ would return 0 for each element in the character vector.
Example 2: Use str_count with Multiple Patterns
The following code shows how to use the str_count() function to count the number of times the letter ‘a’ or the letter ‘s’ occurs in each element in a character vector:
library(stringr)
#create character vector
x <- c('Mavs', 'Cavs', 'Nets', 'Trailblazers', 'Heat')
#count number of times 'a' or 's' occurs in each element in vector
str_count(x, 'a|s')
[1] 2 2 1 3 1
Here’s how to interpret the output:
- The pattern ‘a’ or ‘s’ occurs 2 times in ‘Mavs’
- The pattern ‘a’ or ‘s’ occurs 2 times in ‘Cavs’
- The pattern ‘a’ or ‘s’ occurs 1 time in ‘Nets’
Note: The | symbol represents an “OR” operator in R.
The following tutorials explain how to perform other common tasks in R: