The sub() function in R can be used to replace the first occurrence of certain text within a string in R.

This function uses the following basic syntax:

sub(pattern, replacement, x) 

where:

• pattern: The pattern to look for
• replacement: The replacement for the pattern
• x: The string to search

The following examples show how to use this function in practice.

Note: To replace all occurrences of certain text in a string, use the function instead.

Example 1: Replace One Specific Text in String

The following code shows how to replace the text “cool” with “nice” in a string in R:

#create string
my_string <- 'This is a cool string'

#replace 'cool' with 'nice'
my_string <- sub('cool', 'nice', my_string)

#view updated string
my_string

[1] "This is a nice string"

Notice that “cool” has been replaced with “nice” in the string.

Example 2: Replace One of Several Specific Texts in String

The following code shows how to replace the texts “zebra”, “walrus”, and “peacock” with “dog” if any of them occur in a string:

#create string
my_string <- 'My favorite animal is a walrus'

#replace either zebra, walrus, or peacock with dog
my_string <- sub('zebra|walrus|peacock', 'dog', my_string)

#view updated string
my_string

[1] "My favorite animal is a dog"

Notice that “walrus” has been replaced with “dog” in the string.

Note: The | operator stands for “OR” in R.

Example 3: Replace Numeric Values in String

#create string
my_string <- 'There are 400 dogs out here'

#replace numeric values with 'a lot'
my_string <- sub('[[:digit:]]+', 'a lot of', my_string)

#view updated string
my_string

[1] "There are a lot of dogs out here"

Notice that the numeric value of 400 has been replaced with “a lot” in the string.