Extract string between two "|"

Asked Dec 06 '17 at 10:51

Active Dec 06 '17 at 10:51

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In R, I have a data frame of this kind:

df:

Col.1 Col.2
Apple ab1|cd2|ef3
Pear NULL
Peach mn7|op8|qr9

I am trying to extract the string between "|". In case of NULL, "NULL" (or an equivalent expression) should be displayed, obtaining:

df2:

Col.1 Col.2
Apple cd2
Pear NULL
Peach op8

It seems a very easy operation to me, but I have some problem with regular expressions. I guess something like this one should work:

sub_df <- gsub("(^.+|)("some expression for string bw |" )(|.+$)", "\2", df$Col.2)

If I understood correctly, this should separate each string in Col.2 in three parts, and keeps "part 2". Is that correct? And how to translate that "some expression for string bw |"?

Thank you very much for your help.

asked Dec 06 '17 at 10:51

gmt

You should escape the pipe with double backslash. Actually, same with the `"\\2"` backreference. As for the "some expression...", why haven't you tried `.+`? – Wiktor Stribiżew Dec 06 '17 at 10:54
@WiktorStribiżew You're a bit trigger happy on duplicates these days. – Tim Biegeleisen Dec 06 '17 at 10:55
@WiktorStribiżew I disagree this is a duplicate, but thanks for your answer, it helped a lot! :) – gmt Dec 06 '17 at 11:21
Your main problem here is escaping special char (`|`) in a regex, so it is a dupe. Glad to help. – Wiktor Stribiżew Dec 06 '17 at 11:22

Extract string between two "|"

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