CODEWITHSUNDEEP
rregexstring
user10745594
user10745594

Reputation:

How to find multiple underscore in the same string?

I have strings with different numbers of underscores. I am trying to select the strings that contain two or more underscores. Any suggestions? 

Strings <- c("aa_bb", "aa_bb_cc_dd", "jah_ghtfv_jal")

Currently I have:

Match1 <- Strings[grepl("[_].+[_]", Strings) == TRUE,] and
Match2 <- Strings[grepl("_.*_", Strings) == TRUE,]

Both return slightly different counts. Can anyone come up with a better way to count to return strings that have two or more underscores?

In this case I would like to return "aa_bb_cc_dd, "jah_ghtfv_jal".

Thanks!

Upvotes: 0

Views: 312

Answers (2)

neilfws
neilfws

Reputation: 33792

If the strings can take any form and the underscores can appear anywhere (including, for example, just two underscores "__"), you could just count them using stringr::str_count:

library(stringr)
Strings[str_count(Strings, "_") > 1]

Upvotes: 2

Tim Biegeleisen
Tim Biegeleisen

Reputation: 522151

Your current use of grepl is incorrect, and you should be using this:

Match1 <- Strings[grepl("[_].+[_]", Strings)]
Match2 <- Strings[grepl("_.*_", Strings)]

Both of these return identical results, in line with what you expect. But, I think what you really here is:

Strings <- c("aa_bb", "aa_bb_cc_dd", "jah_ghtfv_jal")
Strings[grepl("_[^_]+_", Strings)]

[1] "aa_bb_cc_dd"   "jah_ghtfv_jal"

This matches any string which has an underscore, followed by one or more non underscore characters, followed by a second underscore.

Upvotes: 0

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