Regular Expression

RegEx Functions

Action	Function
Search for a substring within a string	grep(substring/value, string)
Replace a single value within a string	sub(pattern, replacement, string)
Replace all instances within a string	gsub(pattern, replacement, string)
Find matches for exact string	grepl(pattern, string)

Inputs:

#Search for substring in a string
y <- c("carrot", "apple", "banana", "carrot")
grep("carrot", y)

#Replace a single value within a string
sub("r”, “R”, y)

#Replace all instances within a string
gsub(“r”, “R”, y)

#Find matches of exact strings
grepl("car", y)

Outputs:

#Search for value in a string
1 4
#Returns the position of the value searched for

#Replace the first instance of a single value within a string
"caRrot" "apple" "banana" "caRrot" 

#Replace all instances within a string
"caRRot" "apple" "banana" "caRRot"

#Find matches of exact strings
TRUE FALSE FALSE TRUE

Resources

• DataCamp: Regular Expression