On Dec 11, 2012, at 10:10 AM, jim holtman wrote:
try this:
x
[1] "OYS-PIA2-FL-1" "OYS-PIA2-LA-1" "OYS-PI-LA-BB-1" "OYS-PIA2-
LA-10"
sub("^.*?([0-9]+)$", "\\1", x)
[1] "1" "1" "1" "10"
Steve;
jim holtman is one of the jewels of the rhelp world. I generally
assume that his answers are going to be the most succinct and
efficient ones possible and avoid adding noise, but here I thought I
would try to improve. Thinking there might be a string-splitting
approach I first tried (and discovered a not-so-great solution:
x <- c("OYS-PIA2-FL-1", "OYS-PIA2-LA-1", "OYS-PI-LA-BB-1", "OYS-
PIA2-LA-10")
sapply( strsplit(x, "-") , "[", 4)
[1] "1" "1" "BB" "10"
So then I asked myself if we could just "blank out" everything before
the last das, finding what seemed to be a fairly economical solution
and one that does not require back-references:
sub( "^.+-" , "", x)
[1] "1" "1" "1" "10"
If there were no digits after the last dash these approaches give
different results:
x <- c("OYS-PIA2-FL-1", "OYS-PIA2-LA-1", "OYS-PI-LA-BB-1", "OYS-
PIA2-LA-")
sub( "^.+-" , "", x)
[1] "1" "1" "1" ""
sub("^.*?([0-9]+)$", "\\1", x)
[1] "1" "1" "1" "OYS-PIA2-LA-"
When a grep pattern does not match, sub and gsub will return the whole
argument.
--
David.
On Tue, Dec 11, 2012 at 12:46 PM, Steven Ranney <steven.ran...@gmail.com
> wrote:
OYS-PIA2-FL-1
OYS-PIA2-LA-1
OYS-PI-LA-BB-1
OYS-PIA2-LA-10
--
Jim Holtman
Data Munger Guru
What is the problem that you are trying to solve?
Tell me what you want to do, not how you want to do it.
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David Winsemius, MD
Alameda, CA, USA
______________________________________________
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