If there is nothing there, then R can't know that you want the nothing to be negative.
Patrick Burns
Burns Statistics [EMAIL PROTECTED] +44 (0)20 8525 0696 http://www.burns-stat.com (home of S Poetry and "A Guide for the Unwilling S User")
David Orme wrote:
Hi,
I got caught out by this behaviour in 1.8.0 and I wondered why this happens:
I have a list of vectors and was using lapply and grep to remove matched elements that occur in only a subset of the elements of the list:
locs <- lapply(locs, function(x){x[- grep("^x", x)]})
The problem is that where the grep finds no matches and hence returns a vector of length 0, all the elements of x were removed, rather than none. As a toy example:
vect <- 1:10
vect[-5]
index <- 5
vect[-index]
index <- numeric()
vect[-index] # I was expecting this to give all the elements of vect rather than an empty vector
vect[index] # does the same thing
Thanks, David
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