You need to think about it just a bit harder. [Hint: what happens if you leave out the first 'which' and just make
ids <- (d[, 1] > 0) does it work then...?] -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Werner Wernersen Sent: Monday, 18 April 2005 3:13 AM To: r-help@stat.math.ethz.ch Subject: [R] array indexing and which Hi R friends! I am stuck with a stupid question: I can circumvent it but I would like to understand why it is wrong. It would be nice if you could give me a hint... I have an 2D array d and do the following: ids <- which(d[,1]>0) then I have a vector gk with same column size as d and do: ids2 <- which(gk[ids]==1) but I can't interprete the result I get in ids2. I get the expected result when I use: which(gk==1 & d[,1]>0) Why is the first version wrong? The reason why I try to use the ids vectors is that I want to avoid recomputation. Thanks for your help! Werner ______________________________________________ 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 ______________________________________________ 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