Petr,
Here is a different approach. It, in effect, works from the end of the
string backwards, rather than from the beginning of the string forwards.
substring(x, regexpr("[0-9]+$", x))
The regular expression "[0-9]+$" finds a string of 1 or more ("+")
digits ("[0-9]") followed by the end of the line ("$"). The regexpr()
function returns the position in the string x where that regular
expression begins. Feed that to substring() and you get the desired
result. Both substring() and regexpr() work on vectors of strings.
Best regards,
Chuck Taylor
TIBCO Spotfire Seattle
-----Original Message-----
From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org]
On Behalf Of Petr PIKAL
Sent: Wednesday, July 29, 2009 6:10 AM
To: r-h...@stat.math.ethz.ch
Subject: [R] regexpr virtue
Hi all
I have got something like that (actually those are column names)
[51] "X19.2.300b...80" "X19.2.400v...80" "X19.2.400b...80"
"X19.2.300v...90" "X19.2.300b...90"
[56] "X19.2.400v...90" "X19.2..400b..90" "X19.2.300v...100"
"X19.2.300b...100" "X19.2.400v...100"
in character vector. I would like to get last n figures from this
character vector but my regexpr unerstanding is inferior and I did not
succeed.
Please, is there anybody who can extract those n digits from end of each
character string? If there were only 2 digits I could use substr but
there
can be one, two or three digits.
...
Best regards
Petr
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