[R] I know this is wrong, but why?
Stuart Luppescu
s-luppescu at uchicago.edu
Fri Aug 2 22:57:25 CEST 2002
My mind has become corrupted by having to use SAS too much. I wanted to
calculate the difference of elements of two vectors if the signs are the
same. I tried it the corrupted way first:
if (effects1[,3] < 0 & effects0[,3] < 0) {
imprv1 <- effects0[,3] - effects1[,3]
} else if (effects1[,3] > 0 & effects0[,3] > 0) {
imprv1 <- effects1[,3] - effects0[,3]
} else {
imprv1 <- NA
Then I realized it was giving me wrong results, (for one thing, I was
getting no NAs) and I should be doing it ``The R Way'' like this:
imprv1 <- rep(NA, 267)
imprv1[effects1[,3] < 0 & effects0[,3] < 0] <- effects0[,3] - \
effects1[,3]
imprv1[effects1[,3] > 0 & effects0[,3] > 0] <- effects1[,3] - \
effects0[,3]
But what I don't understand is why the first method doesn't work, or at
least why it didn't give me any warning or error messages. Can someone
enlighten me?
(I'm running R 1.5.1 on RedHat Linux 7.3 (intel).)
--
Stuart Luppescu -=- s-luppescu at uchicago.edu
University of Chicago -=- CCSR
才文と智奈美の父 -=- Kernel 2.4.19-pre10-xf
People don't usually make the same mistake twice --
they make it three times, four time, five times...
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