R help - Nov 2009 - optim(.. ,"SANN",..)

I have a problem using optim, so I am hoping someone can help me out with it:

Suppose I have the list:

list(D,R,P)
[[1]]
   V1 V2 V3 V4
1   0  1  0  1
2   1  1  0  0
3   1  0  1  0
4   0  0  1  1
5   0  1  0  1
6   1  1  0  0
7   1  0  1  0
8   0  0  1  1
9   1  0  1  0
10  0  0  1  1

[[2]]
 [1]   23   85   12   73   23   24   25   56   78 1200

[[3]]
      V1
1     25
2     80
3     15
4     60
5     56
6     15
7     20
8     70
9     45
10 12000

and the strange function fr which I want to maximise:

fr<-function(x){y<-x*D
C<-apply(t(apply(y,1,function(c){c[c>0]})),1,prod)
R2<-R*C
w<-R2[R2<P]
g<-sum(w)
return(g)}

v<-c(1,1,1,1,1,1,1,1,1,1)

res <- optim(v, fr, method="SANN",
              control=list(maxit=200, temp=20,v))

I get the following error:
Error in prod(..., na.rm = na.rm) : invalid 'type' (list) of argument

I'm not sure if its because this function is too disjoint to be opimised
using SANN or I am not using optim properly.

Any help or suggestions would be appreciated.

Thanks

I think the issue is in the function fr,

?apply
apply returns a vector or array or list of values

So if the inner apply returns a list (this happens when different  
number of elements in y are positive in different rows) then outer  
apply cannot coerce it into the correct format to apply the product
To see this try

set.seed(1)
v<- runif(12, -10,10)
fr(v)

Nikhil

On 19 Nov 2009, at 6:05PM, lloyd barcza wrote:
> fr<-function(x){y<-x*D
> C<-apply(t(apply(y,1,function(c){c[c>0]})),1,prod)
> R2<-R*C
> w<-R2[R2<P]
> g<-sum(w)
> return(g)}

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