[R] count sequence of integers

Martin Becker martin.becker at mx.uni-saarland.de
Thu Feb 15 11:52:00 CET 2007


Samuel Kemp wrote:
> Hi,
>
> I would like to be able to count a sequence of numbers. For example, given a
> vector of the following integers
>
> (1,1,1,2,2,2,2,3,3,3,3,3,3,1,1,1,1, 3,3)
>
> the function would return
>
> (3, 4, 6, 4,2)
>
> Does anyone have any cool ideas to solve this?
>
>   
Maybe not the most efficient way, but

 >  count <- function (x) diff(c(0,which(diff(x)!=0),length(x)))

should work (for integer sequences!):

 >  x<-c(1,1,1,2,2,2,2,3,3,3,3,3,3,1,1,1,1,3,3)
 >  count(x)
[1] 3 4 6 4 2

Regards,

  Martin

> Any help appreciated.
>
> Regards,
>
> Sam.
>
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>
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