Dear R list,
I have discovered a seemingly peculiar feature when using a matrix to
index itself (yes, this is strange code, which I have now modified to
be more reasonable).
#this makes sense
s <- matrix(1:3,nrow=1)
s[s] #all three elements are shown
#but when I try
s <- matrix(1:2,nrow=1)
s[1] #fine, the first element is shown
s[2] #fine, the second element is shown
s[s] #just the second element is shown -- this is peculiar
#But doing it by columns works for both cases
s <- matrix(1:3,ncol=1)
s[s] #all three elements are shown
#and when I try the same problem down a column
s <- matrix(1:2,ncol=1)
s[1] #fine
s[2] #fine
s[s] #this shows both elements as would be expected
#clearly since I have just one dimension, it would have been better to
s <- 1:2
s[s] #which works as one would expect.
Or, using the array function we get the same problem.
s <- array(1:2,dim=c(1,2))
s[s]
[1] 2
s <- array(1:2,dim=c(2,1))
s[s]
[1] 1 2
sessionInfo()
R version 2.11.0 Under development (unstable) (2010-03-24 r51389)
i386-apple-darwin9.8.0
locale:
[1] en_US.UTF-8/en_US.UTF-8/C/C/en_US.UTF-8/en_US.UTF-8
attached base packages:
[1] stats graphics grDevices utils datasets methods base
other attached packages:
[1] psych_1.0-87
I think this is unexpected behavior.
Best wishes,
Bill
--
William Revelle http://personality-project.org/revelle.html
Professor http://personality-project.org
Department of Psychology http://www.wcas.northwestern.edu/psych/
Northwestern University http://www.northwestern.edu/
Use R for psychology http://personality-project.org/r
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