[R] Regular expressions & sub

[Peter Dalgaard]

Dirk Eddelbuettel <edd at debian.org> writes:

> Bernd Weiss <bernd.weiss <at> uni-koeln.de> writes:
> > I am struggling with the use of regular expression. I got
> > 
> > > as.character(test$sample.id)
> >  [1] "1.11"   "10.11"  "11.11"  "113.31" "114.2"  "114.3"  "114.8"  
> > 
> > and need
> > 
> > [1] "11"   "11"  "11"  "31" "2"  "3"  "8"
> > 
> > I.e. remove everything before the "." .
> 
> Define the dot as the hard separator, and allow for multiple digits before it:
> 
> > sample.id <- c("1.11", "10.11", "11.11", "113.31", "114.2", "114.3", "114.8")
> > gsub("^[0-9]*\.", "", sample.id)
> [1] "11" "11" "11" "31" "2"  "3"  "8" 

Or, more longwinded, but with less assumptions about what goes before
the dot:

> gsub("^.*\\.(.*)$","\\1",sample.id)
[1] "11" "11" "11" "31" "2"  "3"  "8"

or,

> gsub("^.*\\.([^.]*)$","\\1",sample.id)
[1] "11" "11" "11" "31" "2"  "3"  "8"


-- 
   O__  ---- Peter Dalgaard             Øster Farimagsgade 5, Entr.B
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