Difference between Grep() vs Grepl() in R

In this article, we will discuss the difference between Grep() and Grepl() in R Programming Language.

The two functions grep() and grepl() let you check whether a pattern is present in a character string or vector of a character string, but they both return different outputs:

• Grep() return vector of indices of the element if a pattern exists in that vector.
• Grepl() return TRUE if the given pattern is present in the vector. Otherwise, it return FALSE

The grep() is a built-in function in R. It searches for matches for certain character patterns within a character vector. The grep() takes pattern and data as an argument and return a vector of indices of the character string.

Syntax:

grep(“pattern”, x)

Parameter:

• Pattern- The pattern that matches with given vector element
• x – specified character vector  

Example: Program to show usage of grep()

R

# code
x <- c('Geeks', 'GeeksforGeeks', 'Geek',
       'Geeksfor', 'Gfg')

# calling grep() function
grep('Geek', x)

Output:

 [1] 1 2 3 4

The grepl() stands for “grep logical”. In R it is a built-in function that searches for matches of a string or string vector. The grepl() method takes a pattern and data and returns TRUE if a string contains the pattern, otherwise FALSE.

Syntax:

grep(“pattern”, x)

Parameter:

• Pattern- The pattern that matches with given vector element
• x – specified character vector

Example: Program to show the usage of grepl()

R

# Code
x <- c('Geeks', 'GeeksforGeeks', 'Geek',
       'Geeksfor', 'Gfg')

# calling grepl() function
grepl('for', x)

Output:

[1] FALSE  TRUE FALSE  TRUE FALSE

Both functions need a pattern and x argument, where the pattern is the regular expression you want to match for, and the x argument is the character vector from which you can match the pattern string.

grep() and grepl() functions are help you to search data in the fastest manner when there is a huge amount of data present.

grep()	grepl()
It returns the indices of vector if pattern exist in vector string	It Return TRUE or FALSE if pattern   exist in vector string
grep stands for globally search for a  regular expression	grepl stands for grep logical
Syntax:  grep(“pattern”, x)	Syntax:  grep(“pattern”, x)
Ex: x->c(‘Geeks’,’Geeksfor’,’GFG’)           grep(‘Geeks’, x) o/p-[1] 1 2	Ex: c(‘Geeks’,’Geeksfor’,’GFG’)      grepl(‘Geeks’, x) o/p-[1] TRUE TRUE FALSE