On Apr 22, 2010, at 11:39 AM, Steve Lianoglou wrote:
Hi,
On Thu, Apr 22, 2010 at 11:21 AM, Muhammad Rahiz
<muhammad.ra...@ouce.ox.ac.uk> wrote:
Hi all,
I would like to get the array index for a range of values, say 0 <
x < 1.5.
I'm wondering if there is an alternative for the following which
I've done
x0 <- rnorm(100)
x1 <- ifelse(x0 > 0 & x0 < 1.5,"t","f")
x2 <- which(x1=="t",arr.ind=TRUE)
x0[x2]
Two things:
1. Not that it really matters, but why are you using arr.ind=TRUE when
x0 is just a "normal" vector?
2. Just skip the middle-man creation of x1:
R> x0 <- rnorm(100)
R> x2 <- which(x0 > 0 & x0 < 1.5)
R> x0[x2]
Why not just skip the middle man (x1)?
Or just skip all the middle-men:
x0[ which(x0 > 0 & x0 < 1.5) ]
And further simplification with logical indexing:
x0[ x0 > 0 & x0 < 1.5 ]
--
David.
--
Steve Lianoglou
Graduate Student: Computational Systems Biology
| Memorial Sloan-Kettering Cancer Center
| Weill Medical College of Cornell University
Contact Info: http://cbio.mskcc.org/~lianos/contact
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David Winsemius, MD
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