On 09/21/2010 09:47 PM, kurt_h...@nps.gov wrote:
> All
> Is there a script in R equivalent to the "if then" transforms one can
> perform in Systat? For example, I want to create a "Treatment" column
> coded either 1 or 2 for twelve field sites in a large data set. Ideally,
> I'd be able to tell R to code sites a-f as 1 and sites g-l as 2.
> Cheers
> Kurt
Well, er, sort of.
Actually, there are multiple techniques in R to achieve the same effects
as you'd get using if statements in other languages.
e.g.
f.new <- f
levels(f.new) <- rep(1:2, each=6)
or
f.new <-f
levels(f.new) <- list("1"=letters[1:6],"2"=letters[7:12])
or
f.new <- factor(rep(1:2, each=6))[f]
or
f.new <- (as.numeric(f) > 6) + 1
or
f.new <- factor(ifelse(as.numeric(f) <= 6), 1, 2))
--
Peter Dalgaard
Center for Statistics, Copenhagen Business School
Phone: (+45)38153501
Email: pd....@cbs.dk Priv: pda...@gmail.com
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