On Oct 12, 2009, at 3:22 AM, tdm wrote:
Thanks - would never have guessed that. I eventually got the
following to do
what I want...
colprob <- array(dim=NCOL(iris))
for(i in 1:NCOL(iris)){
+ colprob[i]=
+ ifelse(names(iris)[i] == 'Species',1,0.5)
+ }
colprob
[1] 0.5 0.5 0.5 0.5 1.0
This would be more in keeping with the approah in R of avoiding loops
when possble:
> colprob <- array(dim=NCOL(iris))
> colprob[] <- 0.5
> colprob
[1] 0.5 0.5 0.5 0.5 0.5
> colprob[names(iris) == "Species"] <- 1
> colprob
[1] 0.5 0.5 0.5 0.5 1.0
--
David
Schalk Heunis-2 wrote:
Hi Phil
Try the following
which(names(iris)=='Species')
[1] 5
HTH
Schalk Heunis
On Mon, Oct 12, 2009 at 8:53 AM, tdm <ph...@philbrierley.com> wrote:
Hi,
How do I access the index number of a field given I only know the
field
name?
eg - I want to set the probability of the field 'species' higher
than the
other fields to use in sampling.
colprob <- array(dim=NCOL(iris))
for(i in 1:NCOL(iris)){colprob[i]=0.5}
colprob[iris$species] = 1 #this doesn't work
colprob
[1] 0.5 0.5 0.5 0.5 0.5
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David Winsemius, MD
Heritage Laboratories
West Hartford, CT
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