Gabor;
Did you perhaps get an undesired doubling of "!"?
> x1 <-c("A", "A", "B", "B", "B", "A")
> x1[2:length(x1)] == x1[1:(length(x1)-1)]
[1] TRUE FALSE TRUE TRUE FALSE
> !!diff(c(factor(x1)))
[1] FALSE TRUE FALSE FALSE TRUE
(Your trick of computing differences of the underlying factor
representation ... ganz raffiniert.)
--
David Winsemius
On Jun 1, 2009, at 6:21 PM, Gabor Grothendieck wrote:
Try this:
c(FALSE, !!diff(c(factor(x))))
On Mon, Jun 1, 2009 at 11:57 AM, liujb <liujul...@yahoo.com> wrote:
Hello,
I have a vector:
x <- c("A", "A", "A", "B", "A", "A", "C")
I'd like to compare each of elements of vector x from its previous
element
(except for the 1st element which does not have previous element).
So I'd
like to get a vector y (of same length) that looks something like
(0, 0, 0, 1, 1, 0, 1) or
(F, F, F, T, T, F, T)
Is there a command that do this?
I was thinking to construct another variable x1 from x as follows:
x1 <- vector(length=length(x))
x1[1] <- x[1]
x1[2:length(x)] <- x[1:(length(x)-1)]
x1
Now, x1 is ("A" "A" "B" "B" "B" "A"). However, I don't know how to
compare 2
vectors (of same length) elements by elements and a vector that
indicates
change or no change.
Or there is a easier way to do this?
Thank you very much
Julia
David Winsemius, MD
Heritage Laboratories
West Hartford, CT
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