[R] Subset using grepl

[Kang Min]

Thanks Prof Ripley, the condition worked!
Btw I tried to search ?repl but I don't have documentation for it. Is
it in a non-basic package?


On Jan 29, 6:54 pm, Prof Brian Ripley <rip... at stats.ox.ac.uk> wrote:
> The grep comdition is "[A-J]"
>
> BTW, why there are lots of unnecessary steps here, including using
> cbind() and subset():
>
> x <- rep(LETTERS[1:20],3)
> y <- rep(1:3, 20)
> z <- paste(x,y, sep="")
> random.data <- rnorm(60)
> data <- data.frame(z, random.data)
> data[grepl("[A-J]", z), ]
>
> Now (for the paranoid and not needed in this example) in general the
> effect of "[A-Z]" depends on the locale, so you could write out
> "[ABCDEFIJK]" or create it by
>
> cond <- paste("[", paste(LETTERS[1:10], collapse=""), "]", sep="")
>
> Or use repl("[A-J]", z, perl=TRUE).
>
>
>
> On Sat, 29 Jan 2011, Kang Min wrote:
> > Hi all,
>
> > I would like to subset a dataframe by using part of the level name.
>
> > x <- rep(LETTERS[1:20],3)
> > y <- rep(1:3, 20)
> > z <- paste(x,y, sep="")
> > random.data <- rnorm(60)
> > data <- as.data.frame(cbind(z, random.data))
>
> > I need rows that contain the letters A to J, so I tried:
>
> > subset(data, grepl(LETTERS[1:10], z)) # got only rows with A
> > subset(data, z %in% LETTERS[1:10]) # got no rows
>
> > I think I'm getting close to the solution but need a little bit of
> > help here, thanks in advance.
>
> > Kang Min
>
> > ______________________________________________
> > R-h... at r-project.org mailing list
> >https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guidehttp://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
>
> --
> Brian D. Ripley,                  rip... at stats.ox.ac.uk
> Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
> University of Oxford,             Tel:  +44 1865 272861 (self)
> 1 South Parks Road,                     +44 1865 272866 (PA)
> Oxford OX1 3TG, UK                Fax:  +44 1865 272595
>
> ______________________________________________
> R-h... at r-project.org mailing listhttps://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guidehttp://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.