[R] Replace two nested loop with an apply kind of function

ginan at metu.edu.tr ginan at metu.edu.tr
Sun Aug 25 09:30:00 CEST 2013


Dear Professor, thank you very much your suggestion. Yes, the real problem
is the speed. I will check and try to understand how to use that  R
package, although it seems that it requires some knowledge of C++.

Thank you very much once again,

gul




> The only reason to use one of the apply family of functions is because the
> idiom makes your code more clear. I do not see how that would be the case
> here. The apply functions are not typically any faster. If you really need
> speed the Rcpp package is very easy to use.
>
> Mark
> On Aug 23, 2013, at 3:33 PM, ginan at metu.edu.tr wrote:
>
>>
>>
>> Dear R users,
>>
>> I am confused with the usage of apply kind of functions instead of
>> nested
>> loops. Let me illustrate my problem, I have an array,named C, with
>> dimesions c(nr,nr,nt*n). I want to fill in a Tmat array according to the
>> rule as given below:
>>
>> Tmat<-array(diag(nt*nr), c(nt*nr,nt*nr,n))
>>
>> for( i in 1:n)  {
>> for( t in 2:nt) {
>> Tmat[(2*t-1):(2*t),(2*t-3):(2*t-2),i]<-C[,,(i*t)]
>> }
>> }
>>
>> Instead of using two for loops, I want to use any apply kind of
>> function,
>> but I couldn't figure it out. At this point, any help will be
>> appreciated.
>> Thank you very much for your interest.
>>
>>
>> gul
>>
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>
>



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