Subset using grepl
On Sat, 29 Jan 2011, Kang Min wrote:
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?
I meant grepl: the edit messed up (but not on my screen, as sometimes happens when working remotely). The point is that 'perl=TRUE' guarantees that [A-J] is interpreted in ASCII order.
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
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-- 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.
______________________________________________ R-help at r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Brian D. Ripley, ripley 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