You haven't told us the dimension of the array, which is useful to
when deciding on approach, especially 'm'. /H
On Mon, Mar 28, 2011 at 5:56 PM, Giuseppe <neo...@gmail.com> wrote:
> Dennis,
>
> Yes, Reduce works, but unfortunately it does not speed up the
> evaluation time (actually, it makes it a little bit slower).
>
> Thank you anyway.
>
>
>
> On Tue, Mar 29, 2011 at 2:21 AM, Dennis Murphy <djmu...@gmail.com> wrote:
>> Hi:
>>
>> Is this what you're after?
>>
>> m <- array(1:27, c(3, 3, 3))
>> xx <- 1:3
>> Reduce('+', lapply(xx, function(k) xx[k] * m[, , k]))
>>
>>> m
>> , , 1
>>
>> [,1] [,2] [,3]
>> [1,] 1 4 7
>> [2,] 2 5 8
>> [3,] 3 6 9
>>
>> , , 2
>>
>> [,1] [,2] [,3]
>> [1,] 10 13 16
>> [2,] 11 14 17
>> [3,] 12 15 18
>>
>> , , 3
>>
>> [,1] [,2] [,3]
>> [1,] 19 22 25
>> [2,] 20 23 26
>> [3,] 21 24 27
>>
>>> xx <- 1:3
>>> Reduce('+', lapply(xx, function(k) xx[k] * m[, , k]))
>> [,1] [,2] [,3]
>> [1,] 78 96 114
>> [2,] 84 102 120
>> [3,] 90 108 126
>>
>> HTH,
>> Dennis
>>
>>
>> On Mon, Mar 28, 2011 at 4:10 PM, Giuseppe <neo...@gmail.com> wrote:
>>>
>>> I have the following situation.
>>>
>>> H12 is an array of dimension (n,k,m) and hessian_lambda is a numeric
>>> of length m.
>>>
>>> I need to multiply each matrix H12[,,1], H12[,,2], ..., H12[,m] by
>>> hessian_lambda[1], hessian_lambda[2], ..., hessian_lambda[m],
>>> respectively, and then add the resulting (n,k) matrices. What I am
>>> using at the moment is the following code:
>>>
>>> H <- matrix(0, n, k)
>>> for(j in 1:(m)) {
>>> H <- H + H12[,,j]*hessian_lambda[j]
>>> }
>>>
>>> Does anybody see a way to speed up this without using loop? (The
>>> output needs to be a matrix).
>>>
>>> Thank you for your time.
>>>
>>> ______________________________________________
>>> R-help@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.
>>
>>
>
> ______________________________________________
> R-help@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.
>
______________________________________________
R-help@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.
