RE: [R] array indexing and which

From: <>
Date: Mon 18 Apr 2005 - 08:54:51 EST

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-----
[] On Behalf Of Werner Wernersen
Sent: Monday, 18 April 2005 3:13 AM
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 mailing list PLEASE do read the posting guide! mailing list PLEASE do read the posting guide! Received on Mon Apr 18 11:11:07 2005

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