I have an R string, with the format
s = `"[some letters and numbers]_[a number]_[more numbers, letters, punctuation, etc, anything]"`
I simply want a way of checking if s
contains "_2"
in the first position. In other words, after the first _
symbol, is the single number a "2"? How do I do this in R?
I'm assuming I need some complicated regex expresion?
Examples:
39820432_2_349802j_32hfh = TRUE
43lda821_9_428fj_2f = FALSE
(notice there is a _2
there, but not in the right spot)
> grepl("^[^_]+_1",s)
[1] FALSE
> grepl("^[^_]+_2",s)
[1] TRUE
basically, look for everything at the beginning except _
, and then the _2
.
+1 to @Ananda_Mahto for suggesting grepl
instead of grep
.
I think it's worth answering the generic question "R - test if string contains string" here.
For that, use the grep function.
# example:
> if(length(grep("ab","aacd"))>0) print("found") else print("Not found")
[1] "Not found"
> if(length(grep("ab","abcd"))>0) print("found") else print("Not found")
[1] "found"
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