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()

# 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()

# 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.