R - test if first occurrence of string1 is followed by string2

contains, r

Solution

> 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`.

Problem

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)

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