Counting value changes

x <- c(0,1,0,1,0,0,0,1,1,1,0,0,0,1)
# lets keep count of the 4 different transitions that can happen
indx <- cbind(head(x, -1), tail(x, -1)) %*% c(2, 1)
table(indx) # 0=0-0, 1=0-1, 2=1-0, 3=1-1

Just for clarity, I changed your x a bit - in your version, the 0-1 and 1-0
change occurred the same number of times.

If all your values are 0 and 1, this will work:

x <- c(0,1,0,1,0,0,0,1,1,1)
table(diff(x))

-1 ?0 ?1
?2 ?4 ?3

sum(diff(x) == 1)

[1] 3

If other values can occur, it would need some tweaking.

Sarah

On Sat, Feb 18, 2012 at 2:09 PM, maris478 <maris478 at gmail.com> wrote:

Good afternoon,
I've encountered a little bit of a problem, would appreciate any help here.

I made a small vector consisting of ones and zeros.
Something like this x <- c(0,1,0,1,0,0,1,0), and all I need is to count how
many times "0" becomes "1".
Tried various, of what I thought, methods with built in functions. Didn't
get any further.

Thank you very much.

--
Sarah Goslee
http://www.functionaldiversity.org