R help - Oct 2009 - Need help locating the longest series of consecutive numbers in a matrix

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

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
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>


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

What is the problem that you are trying to solve?