is there a function like %in% for characters?

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

Be sure to read up on regular expressions if pursuing this option.

HTH,

--sundar

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