[R] Fwd: Empty list to use in a for cycle

[Vincent Goulet]

Le lun. 26 nov. à 10:35, Niccolò Bassani a écrit :

> Dear R-users,
> I'm posting a problem I already asked help for some time ago,  
> because I'm
> facing that problem once again and even because now, reading that old
> e-mail, and the answer recevied, I understand I've not made myself  
> clear.
>
> Here's the question: I need to create an empty list of a specific  
> length to
> fill it with a quite large amount of square matrices, which is 602.  
> The
> question is that these matrices are created inside a for cycle, and  
> I do not
> know how to recall all of them one by one, except by creating an  
> empty list
> before the cycle, than assigning for each value of the i index the  
> amtrix
> computed to the first element of the empty list.
> The fact is that: i've trided to create an empty list with
>
> vector("list",602)
>
> and then putting it in a cycle, but it didn't work. This is the  
> cycle I've
> used. To prove it works (and then the cycle itself is not a problem)  
> there's
> also the output (i.e. the last square matrix computed).
>
> for (i in unique(elio2$id)){
> sub.mu <- exp.mu[exp.mu$id==i,]
> D <- matrix(0,nrow( sub.mu),nrow(sub.mu))
> diag(D) <- sub.mu$deriv.link
> A <- mat.cov[1:nrow(D),1:nrow(D)]
> R <- corstr[1:nrow(D),1:nrow(D)]
> W <- solve(D)%*%solve(sqrt(A))%*%solve(R)%*%solve(sqrt(A))%*%solve(D)
> }

You do not seem to use your index i. And what is W? The following  
should do what you want:

W <- vector("list", 602)

for (i in unique(elio2$id))
{
     sub.mu <- exp.mu[exp.mu$id==i,]
     D <- matrix(0,nrow( sub.mu),nrow(sub.mu))
     diag(D) <- sub.mu$deriv.link
     A <- mat.cov[1:nrow(D),1:nrow(D)]
     R <- corstr[1:nrow(D),1:nrow(D)]
     W[[i]] <- solve(D)%*%solve(sqrt(A))%*%solve(R)%*%solve(sqrt(A))%* 
%solve(D)
}


HTH

Vincent

>
>
>> W
>              [,1]          [,2]          [,3]          [,4]
> [1,]  3.492489e+02 -7.9324883721  0.0006286788 -0.0031046240
> [2,] -7.932488e+00 17.4974625191 -1.7575467817  0.0001403319
> [3,]  6.286788e-04 -1.7575467817 17.3227959738 -1.7529916860
> [4,] -3.104624e-03  0.0001403319 -1.7529916860 17.2279244622
>>
>
> Does anyone knows how to insert each and every matrix like the one  
> above in
> a "omnicomprehensive" list? That's because I've to use a function  
> requiring
> me to have the matrices I need inside a list.
> Thanks in advance, hope it's not a too much stupid problem!
> niccolò
>
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>
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---
   Vincent Goulet, Associate Professor
   École d'actuariat
   Université Laval, Québec
   Vincent.Goulet at act.ulaval.ca   http://vgoulet.act.ulaval.ca