[R] cumsum in 3d arrays

[David Winsemius]

On Nov 26, 2011, at 11:24 AM, David Winsemius wrote:

>
> On Nov 26, 2011, at 9:32 AM, zloncaric wrote:
>
>> Hello!
>>
>> Is it posible to apply /cumsum()/ along the 3rd dimension of 3D  
>> array?
>> Something like matrlab function - /cumsum (*A*,dim)/ which returns  
>> the
>> cumulative sum of the elements along the dimension of *A* specified  
>> by
>> scalar dim.
>>
>
> `apply` lets you chose which dimension gets selected.
>
> Perhaps:
>
> apply(mat, 3, cumsum)

Or perhaps

  apply(mat, 1:2, cumsum)

>
> (This is pretty basic stuff so you should probably be reading or at  
> least skimming somewhat more thoroughly than you have so far the  
> Introduction to R document and there is also the R for Matlab  
> document by Bob Muenchen ... and a compendium of equivalencies by  
> Hiebeler at: www.math.umaine.edu/~hiebeler/comp/matlabR.html )
>
> -- 

David Winsemius, MD
West Hartford, CT