[R] Filling matrix elements with a function

[Jessica Streicher]

Not that i really understand what that shall do, but..

why do you define 2 functions that do exactly the same?
why do you want to make a matrix of functions instead of a matrix with the results of functions?

On 06.11.2012, at 05:11, Aimee Kopolow wrote:

> Hi all,
> 
> 
> I have a matrix simulating migration in a spatial model. I want to be
> able to define movement (the values of m1, m2 and m3) as only != 0
> between adjacent patches and contingent on certain conditions as
> defined in the function.
> 
> Here is the code:
> 
> WET<-function(t) {everglades$precipitation[t]}    #simply reads
> precipitation data from a csv, value is numeric
> 
> AB<-function(WET,t) {ifelse(WET(t)>0, 0.0001, 0)}
> BC<-function(WET,t) {ifelse(WET(t)>0, 0.0001, 0)}
> 
> NP<-4
> m1 <- matrix(0, NP,NP)
>  m2 <- matrix(0,NP,NP)
>  m3 <- matrix(0,NP,NP)
> 
> 
> for (i in 1:NP)
>  {
>   for (j in 1:NP)
>   {
>    if ((i%%sqrt(NP)) == 0 & i!=j)
>    {
>     if(j == i+sqrt(NP) | j == i-1 | j == i-sqrt(NP))
>     {
>      m1[j,i] <- AB
>      m1[i,j] <- AB
> 
> 
>      m2[j,i] <- 0.00025
>      m2[i,j] <- 0.00025
> 
>      m3[j,i] <- BC
> 
>      m3[i,j] <- BC
> 
>     }
>    }
>    if (i%%sqrt(NP) == 1)
>    {
>     if(j == i+sqrt(NP) | j == i+1 | j == i-sqrt(NP) )
>     {
>      m1[j,i] <- AB
> 
>      m1[i,j] <- AB
> 
> 
>      m2[j,i] <- 0.00025
>      m2[i,j] <- 0.00025
> 
>      m3[j,i] <- BC
> 
>      m3[i,j] <- BC
>     }
>    }
> 				
>    if (i%%sqrt(NP)!=0 & i%%sqrt(NP)!=1 & i!=j)
>    {
>     if(j == i+sqrt(NP) | j == i+1 | j == i-sqrt(NP) | j == i-1)
>     {
>      m1[j,i] <- AB
> 
>      m1[i,j] <- AB
> 
>      m2[j,i] <- 0.00025
>      m2[i,j] <- 0.00025
> 
>      m3[j,i] <- BC
> 
>      m3[i,j] <- BC
>      }
>    }
>   }
>  }
> 
> Please could somebody advise me as to where I'm going wrong and how to
> get it right? I have tried several different permutations and can't
> seem to do so. I tried googling keywords "inserting function as matrix
> element" but couldn't find any advice online. I'm very inexperienced
> at coding so apologies if this is very simple.
> 
> Thank you for any assistance you are able to give,
> Aimee.
> 
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