Hi all
I have a regex question I can't solve. I know this is a realy long posting but
in order to explain the problem, I first say what I can do and then what I
can't. Any ideas, pointers, snippets of code etc. would be really appreciated
...
Thx,
STG
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I. This I can do ...
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I have an array @a with character strings:
@a=("<w AT0>a <w CJC>and <w DT0>that<c PUN>.",
"<w AT0>a <w CJC>and <w AJ0>hungry <c PUN>,<w DT0>that<c PUN>.")
"<w AT0>a <w CJC>and <w AJ0>hungry <w AJ0>hungry <c PUN>,<w DT0>that<c PUN>.")
The defining characteristic of the character strings in the array are that
every word and every punctuation mark is preceded by a tag with the following
structure: /<(w ...(-...)?|c ...)>/
(a) I want to retrieve the sequence of
- a word tagged as <w CJC>, immediately followed by
- a word tagged as <w DT0>.
Since every tag starts with /</, I use this regex: /<w CJC>[^<]*?<w DT0>[^<]*/,
which works just fine by retrieving only @a[0].
(b) I want to retrieve the sequence of
- a word tagged as <w CJC>, followed by
- between 0 and 2 words and their tags (again, looking like this: /<(w
...(-...)?|c ...)>/), followed by
- a word tagged as <w DT0>.
I use this regex: /<w CJC>[^<]*?(<[wc] (...|...-...)>[^<]*?){0,2}<w DT0>[^<]*/,
which works just fine by retrieving only @a[0:1]. (I know I could use "?:" to
avoid the capturing for the backreference but I don't care about that at the
moment.)
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II. This I can't ...
----------------------
I have an array @b with character strings:
@b=("<w AT0>a <w CJC>and <w DT0>that<c PUN>.",
"<w AT0>a <w CJC>and <w DT0>that <w NN2>cars",
"<w AT0>a <w CJC>and <ptr target=KB2LC003><w DT0>that<c PUN>.",
"<w AT0>a <w CJC>and <ptr target=KB2LC003> <w DT0>that<c PUN>.",
"<w AT0>a <w CJC>and <ptr target=KB2LC003> <ptr target=KB2LC004> <w
DT0>that<c PUN>.",
"<w AT0>a <w CJC>and <p tr target=KB2LC003> <ptr target=KB2LC004> <w
DT0>that<c PUN>.",
"<w AT0>a <w CJC>and <wtr target=KB2LC003><w DT0>that<c PUN>.",
"<w AT0>a <w CJC>and <ctr target=KB2LC003><w DT0>that<c PUN>.",
"<w AT0>a <w CJC>and <ptr target=KB2LC003><c PUN>, <w DT0>that<c PUN>.",
"<w AT0>a <w CJC>and <ptr target=KB2LC003><w NN2-VVZ>cars <w DT0>that<c
PUN>.",
"<w AT0>a <w CJC>and <w AJ0>hungry <w DT0>that<c PUN>.",
"<w AT0>a <w CJC>and <w AJ0>hungry <c PUN>,<w DT0>that<c PUN>.")
I basically want to do the same things as above, but the complication is that
there are now additional kinds of tags -- tags that are not /<(w ...(-...)?|c
...)>/ -- and my problem is how to skip them, to disregard them for the match.
Thus,
(a) I want to retrieve those elements of @b in which "<w CJC>" and "<w DT0>" are
- directly adjacent, or
- not interrupted by any word with its tag (again, looking like this: /<(w
...(-...)?|c ...)>/).
That is, I need to say something like "return everything from /<w CJC>/ and /<w
DT0>/ but not if there is any /<(w ...(-...)?|c ...)>/ in between the two, then
return nothing". Thus, of the array @b I would like to get back the first eight
elements, but not the last four elements:
@b[0]: yes, because only separated by a space
@b[1]: yes, because only separated by a space
@b[2]: yes, because not interrupted by /<(w ...(-...)?|c ...)>/, only by
/<ptr[^>]+>/
@b[3]: yes, because not interrupted by /<(w ...(-...)?|c ...)>/, only by
/<ptr[^>]+>/
@b[4]: yes, because not interrupted by /<(w ...(-...)?|c ...)>/, only by
/<ptr[^>]+>/
@b[5]: yes, because not interrupted by /<(w ...(-...)?|c ...)>/, only by /<p
tr[^>]+>/ and /<ptr[^>]+>/
@b[6]: yes, because not interrupted by /<(w ...(-...)?|c ...)>/, only by
/<w[^>]+>/
@b[7]: yes, because not interrupted by /<(w ...(-...)?|c ...)>/, only by
/<c[^>]+>/
@b[8]: no, because interrupted by, among other things, /<c PUN>/
@b[9]: no, because interrupted by, among other things, /<w NN2-VVZ>/
@b[10]: no, because interrupted by, among other things, /<w AJ0>hungry/
@b[11]: no, because interrupted by, among other things, /<w AJ0>/ and /<c PUN>/
I do not use Perl, but R, so the regex
- *must* involve Perl-compatible regular expressions;
- would ideally work without lookaround (but if lookaround is absolutely
needed, so be it).
The best I came up with was this (again, I don't care putting in "?:"): /<w
CJC>[^<]+(<[^wc].*?>.*?)*<w DT0>[^<]*?/ but this does of course not work for
@b[6:7] because the relevant part of the regex only says /<[wc]/, but I need to
rule out all this /<(w ...(-...)?|c ...)>/.
(b) I want to retrieve the sequence of
- a word tagged as <w CJC>, followed by
- between 0 and 2 words and their tags (again, looking like this: /<(w
...(-...)?|c ...)>/), followed by
- a word tagged as <w DT0>.
Again, the regex
- *must* involve Perl-compatible regular expressions;
- would ideally work without lookaround (but if lookaround is absolutely
needed, so be it).
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