From: allan miller <amiller_at_a2software.com>

Date: Wed 11 Jan 2006 - 04:56:18 EST

R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Wed Jan 11 05:02:55 2006

Date: Wed 11 Jan 2006 - 04:56:18 EST

Hello,

I wrote a version of which.na (similar to S's) in R that returns a vector of positions at which NA appears in the target vector v:

which.na<-function(v) {

retv <- c()

for (i in 1:length(v)) {

if (is.na(v[i])) { retv<-append(i, retv, after = length(retv)) }

}

return(retv)

}

nv <- c(2,4,NA,NA)

nas<-which.r(nv)

print(nas)

[run]

* > source("which.r")
*

[1] 4 3

* >
*

Two questions about this:

(1) It seems that append actually "prepends"

(2) Is there a more simpler way to build the vector of positions (versus using append in a loop, as above), using functions such as match() and apply()?

Thank You.

R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Wed Jan 11 05:02:55 2006

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