R help - Dec 2010 - determine length of sequence of equal elements in a vector

Dear list members,


I am seeking a function that returns me the length of a continous 
sequence of identical elements in a vector. Something like (or similar to):


example = c(1,1,1,2,2,3,3,3,3)


result = c(3,3,3,2,2,4,4,4,4)


I am quite sure there already exists a function to do this, I just cant 
figure out its name. Otherwise I would start programming my own function.



Best
Jannis

On 18/12/2010 12:21 PM, Jannis wrote:
> Dear list members,
>
>
> I am seeking a function that returns me the length of a continous
> sequence of identical elements in a vector. Something like (or similar to):
>
>
> example = c(1,1,1,2,2,3,3,3,3)
>
>
> result = c(3,3,3,2,2,4,4,4,4)
>
>
> I am quite sure there already exists a function to do this, I just cant
> figure out its name. Otherwise I would start programming my own function.
The rle() function produces the data in a different format.  Together 
with rep() you can get what you want:

x <- rle(example)
rep(x$lengths, x$lengths)

Duncan Murdoch

Thanks a lot, Duncan.


Duncan Murdoch schrieb:
> On 18/12/2010 12:21 PM, Jannis wrote:
>> Dear list members,
>>
>>
>> I am seeking a function that returns me the length of a continous
>> sequence of identical elements in a vector. Something like (or 
>> similar to):
>>
>>
>> example = c(1,1,1,2,2,3,3,3,3)
>>
>>
>> result = c(3,3,3,2,2,4,4,4,4)
>>
>>
>> I am quite sure there already exists a function to do this, I just cant
>> figure out its name. Otherwise I would start programming my own 
>> function.
>
> The rle() function produces the data in a different format.  Together 
> with rep() you can get what you want:
>
> x <- rle(example)
> rep(x$lengths, x$lengths)
>
> Duncan Murdoch
>