Erik Iverson wrote:
Hello,
Can anyone think of a non-iterative way to generate a decreasing geometric
sequence in R?
For example, for a hypothetical function dg, I would like:
> dg(20)
[1] 20 10 5 2 1
where I am using integer division by 2 to get each subsequent value in the
sequence.
There is of course:
dg <- function(x) {
res <- integer()
while(x >= 1) {
res <- c(res, x)
x <- x %/% 2
}
res
}
> dg(20)
[1] 20 10 5 2 1
This implementation of 'dg' uses an interative 'while' loop. I'm simply
wondering if there is a way to vectorize this process?
Something like this should work, at least for integer bases:
base <- 2
len <- ceiling(log(x, base))
floor(x/base^(seq_len(len)-1))
Duncan Murdoch
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