R match part of string against vector of strings

Question

I have a comma separated character class

A = "123,456,789"

and I am trying to get a logical vector for when one of the items in the character class are present in a character array.

B <- as.array(c("456", "135", "789", "111"))

I am looking for logical result of size 4 (length of B)

[1] TRUE FALSE TRUE FALSE

Fairly new to R so any help would be appreciated. Thanks in advance.

Answer 1

You can use a combination of sapply and grepl, which returns a logical if matched

 sapply(B, grepl, x=A)

Answer 2

Since your comparison vector is comma-separated, you can use this as a non-looping method.

B %in% strsplit(A, ",")[[1]]
# [1]  TRUE FALSE  TRUE FALSE

And one other looping method would be to use Vectorize with grepl. This uses mapply internally.

Vectorize(grepl, USE.NAMES = FALSE)(B, A)
# [1]  TRUE FALSE  TRUE FALSE