Use grepl to search either of multiple substrings in a text [duplicate]

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• Matching multiple patterns 6 answers

I am using grepl() in R to search if either of the following Genres exist in my text. I am doing it like this right now:

grepl("Action", my_text) |
grepl("Adventure", my_text) |  
grepl("Animation", my_text) |    
grepl("Biography", my_text) |  
grepl("Comedy", my_text) |    
grepl("Crime", my_text) |  
grepl("Documentary", my_text) |  
grepl("Drama", my_text) |  
grepl("Family", my_text) |  
grepl("Fantasy", my_text) |  
grepl("Film-Noir", my_text) |  
grepl("History", my_text) |  
grepl("Horror", my_text) |  
grepl("Music", my_text) |  
grepl("Musical", my_text) |  
grepl("Mystery", my_text) |  
grepl("Romance", my_text) |  
grepl("Sci-Fi", my_text) |  
grepl("Sport", my_text) |  
grepl("Thriller", my_text) |  
grepl("War", my_text) |    
grepl("Western", my_text) 

Is there a better way to write this code? Can I put all the genres in an array and then somehow use grepl() on that?

Answer 1

You could paste the genres together with an "or" | separator and run that through grepl as a single regular expression.

x <- c("Action", "Adventure", "Animation", ...)
grepl(paste(x, collapse = "|"), my_text)

Here's an example.

x <- c("Action", "Adventure", "Animation")
my_text <- c("This one has Animation.", "This has none.", "Here is Adventure.")
grepl(paste(x, collapse = "|"), my_text)
# [1]  TRUE FALSE  TRUE

Answer 2

You can cycle through a list or vector of genres, as below:

genres <- c("Action",...,"Western")
sapply(genres, function(x) grepl(x, my_text))

To answer your question, if you just want to know if any element of the result is TRUE you can use the any() function.

any(sapply(genres, function(x) grepl(x, my_text)))

Quite simply, if any element of is TRUE, any will return TRUE.