[R] Regular expression help

[William Dunlap]

"(^| +)([^/ ]*/?){0,2}", with the first "*" replaced by "+" would be a bit
better.

Bill Dunlap
TIBCO Software
wdunlap tibco.com

On Mon, Oct 9, 2017 at 8:50 AM, William Dunlap <wdunlap at tibco.com> wrote:

> > x <- "f 147/1315/587 2820/1320/587 3624/1321/587 1852/1322/587"
> > gsub("(^| *)([^/ ]*/?){0,2}", "\\1", x)
> [1] " 587 587 587 587"
> > y <- "aa aa/ aa/bb aa/bb/ aa/bb/cc aa/bb/cc/ aa/bb/cc/dd aa/bb/cc/dd/"
> > gsub("(^| *)([^/ ]*/?){0,2}", "\\1", y)
> [1] "    cc cc/ cc/dd cc/dd/"
>
>
> Bill Dunlap
> TIBCO Software
> wdunlap tibco.com
>
> On Mon, Oct 9, 2017 at 8:02 AM, Duncan Murdoch <murdoch.duncan at gmail.com>
> wrote:
>
>> I have a file containing "words" like
>>
>>
>> a
>>
>> a/b
>>
>> a/b/c
>>
>> where there may be multiple words on a line (separated by spaces).  The
>> a, b, and c strings can contain non-space, non-slash characters. I'd like
>> to use gsub() to extract the c strings (which should be empty if there are
>> none).
>>
>> A real example is
>>
>> "f 147/1315/587 2820/1320/587 3624/1321/587 1852/1322/587"
>>
>> which I'd like to transform to
>>
>> " 587 587 587 587"
>>
>> Another real example is
>>
>> "f 1067 28680 24462"
>>
>> which should transform to "   ".
>>
>> I've tried a few different regexprs, but am unable to find a way to say
>> "transform words by deleting everything up to and including the 2nd slash"
>> when there might be zero, one or two slashes.  Any suggestions?
>>
>> Duncan Murdoch
>>
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>
>
>

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