[R] is there a function like %in% for characters?

[Douglas Bates]

Sundar Dorai-Raj wrote:
> 
> 
> Terry Mu wrote on 4/2/2005 9:38 PM:
> 
>> like:
>>
>> "a" %in% "abcd"
>> TRUE
>>
>> Thanks.
>>
> 
> 
> See ?regexpr.
> 
> regexpr("a", "abcd") > 0
> 
> However, the first argument is not vectorized so you may also need 
> something like:
> 
>  > sapply(c("a", "b", "e"), regexpr, c("abcd", "bcde")) > 0
>          a    b     e
> [1,]  TRUE TRUE FALSE
> [2,] FALSE TRUE  TRUE

Alternatively you could use strsplit to split the original string into 
individual characters then fall back on %in%.  The only complication is 
that strsplit will return a list of one character vector and you must 
unlist it to get the character vector itself.

 > strsplit("abcf", "")
[[1]]
[1] "a" "b" "c" "f"

 > "a" %in% unlist(strsplit("abcf", ""))
[1] TRUE
 > "a" %in% unlist(strsplit("bcdf", ""))
[1] FALSE