On Jun 8, 2009, at 12:34 PM, Marc Schwartz wrote:
On Jun 8, 2009, at 9:15 AM, Mark Heckmann wrote:
Hi,
i need to recognize itemization structures in strings which follow
the
format: "digit-digit-dot" like e.g.
1.
2.
19.
211.
Given the string " This happened in the 21. century." (the dot
behind 21 is
used in German instead of 21st) I want know where the dots are but
I do not
want the 21.-dot to be returned as well.
I am not good at regular expressions. How can I retrieve or
recognize dots
excluding the digit-digit-dot structure?
TIA, Mark
vec <- c("1.", "2.", "19.", "211.", "This happened in the 21.
century")
> grep("^[0-9]+\\.", vec, value = TRUE)
[1] "1." "2." "19." "211."
The regex "^[0-9]+\\." is interpreted as "match one or more digits
followed by a period, only at the beginning of the line". The caret
'^' defines the beginning of the line, so that a sequence of numbers
followed by a period in the middle of the line will not match.
I mis-read that last part of your query. I see that Henrique and Gabor
have provided what appear to be correct solutions.
Sorry for the confusion.
Marc
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