On Aug 10, 2011, at 9:08 AM, Anthony Ching Ho Ng wrote:
Dear list,
I wonder if there a better way to have rbind/cbind/append to create
the first element (if it is empty) instead of doing the following in a
loop?
for (i in 1:10) {
if (i == 1) {
aRow = SomeExpression(i)
} else {
aRow = rbind(aRow,SomeExpression(i))
}
}
Generally one is advised not to use rbind in this manner but rather to
pre-allocate aRow to the size needed and then to add information by
rows using "[".
For a matrix this might be:
aRow <- matrix(NA, ncol=3, nrow=10)
for (i in 1:10) {
aRow[1,] <- SomeExpression(i)
}
--
David Winsemius, MD
West Hartford, CT
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