Dear all
This is a follow-up to an earlier posting today regarding a regular expression
question. In the meantime, this is the best approximation I could come up with
and should give you a better idea what I am talking about.
a-c(w AT0a w NN1blockage w CJCand w DT0thatc PUN.,
w AT0a w NN1blockage w CJCand ptr target=KB2LC003w DT0thatc
PUN.,
w AT0a w NN1blockage w CJCandc PUN, w DT0thatc PUN.,
w AT0a w NN1blockage w CJCand w AJ0hungry w DT0thatc PUN.)
matches-gregexpr(w CJC[^]+(?:[^wc].*?.*?)*w DT0that, a, perl=TRUE)
starts-unlist(matches)
lengths-unlist(sapply(matches, attributes))
stops-starts+lengths-1
substr(a, starts, stops)
What is still missing is that the disallowed string is not just [wc] but
[wc] and I don't know how to do that. Any ideas (preferably with
lookarounds)?
Thanks a bunch,
STG
--
Stefan Th. Gries
---
University of California, Santa Barbara
http://www.linguistics.ucsb.edu/faculty/stgries
---
ORIGINAL MESSAGE
Dear all
I again have a regular expression question. I have this character vector a:
a-c(w AT0a w NN1blockage w CJCand w DT0thatc PUN.,
w AT0a w NN1blockage w CJCand ptr target=KB2LC003w DT0thatc
PUN.,
w AT0a w NN1blockage w CJCandc PUN, w DT0thatc PUN.,
w AT0a w NN1blockage w CJCand w AJ0hungry w DT0thatc PUN.)
I would like to retrieve those elements of a in which w CJC and w DT0
are
- directly adjacent, as in a[1] or
- not interrupted by [wc] , as in a[2]
And, of these elements I would like to consume all characters from the in
w CJC to the last character after w DT0 that is not a . For
example, if I was only searching a[1], I would like something like this:
matches-gregexpr(w CJC[^]+?w DT0[^]+, a[1], perl=TRUE)
substr(a[1], unlist(matches), unlist(matches)+unlist(attributes(matches[[1]],
match.length))-1)
I have been fiddling around with negative lookahead but I really can't get my
head around this. Any pointers would be greatly appreciated. Thanks a lot,
STG
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