[R] Need help locating the longest series of consecutive numbers in a matrix

[jim holtman]

Use 'rle':

> x <- rle(sample[,2])
> x
Run Length Encoding
  lengths: int [1:9] 10 3 3 1 1 1 1 17 3
  values : num [1:9] 0 1 0 1 0 1 0 1 0
> which.max(x$lengths[x$values==1])
[1] 4
> which.max(x$lengths * x$values)  # makes use of the fact you are only using 0 & 1
[1] 8
> cumsum(c(1, x$lengths))
 [1]  1 11 14 17 18 19 20 21 38 41
> cumsum(c(1, x$lengths))[8]  #  index of the start of the run
[1] 21
> x$lengths[8]  # length of the run
[1] 17
>


On Wed, Oct 28, 2009 at 12:27 PM, Staples, Angela Dawn
<adstaple at indiana.edu> wrote:
> I need to determine the length of the longest series of consecutive numbers
> (1's to be specific) and the start time of that series. For example, in the
> following sample, the first column is "time" and the second column indicates
> the presence of the target behavior.
>
> I would like a function that would return "21" as the start time and "17" as
> the length.
>
> sample <-
> matrix(data=c(1:40,rep(0,10),rep(1,3),rep(0,3),1,0,1,0,rep(1,17),0,0,0),40,2
> )
>
> I would appreciate any suggestions you have.
>
> Respectfully,
> ~ Angela
>
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>



-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem that you are trying to solve?