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POoptimization in R across multiple 'areas'
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2012-10-17T19:51:56.137
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I am building a bioeconomic model of a fishery with multiple areas and fleets. I need to add a cost function to the objective function. The cost function derivative is: <pre><code>dvcost<-(maxeff/(maxeff-(total f))*k*(f/total f)-ln(1-((total f)/maxeff))*k*maxeff/(total f)*(1-(f/total f)) </code></pre> where: for each fleet, f is effort in a specific area where the objective function is being minimized, total f is the sum of effort across areas for a particular fleet. k and maxeff are parameters. My question is: how do I apply this cost function to my problem? I already have total f (which is 'f' in the code), but I need to find the f for the area that the objective function is working over. Any suggestions are much appreciated. Thanks! The full code is below: CODE <pre><code>nfleets<-2 nareas<-2 M<-1 M<-array(M,dim=c(nfleets,nareas)) N<-1000 cost<-c(30,30) cost<-array(cost,dim=c(nfleets,nareas)) Price<-2 Price<-array(Price,dim=c(nfleets,nareas)) q<-array(0.1,dim=c(nfleets,nareas)) f<-1 f<-array(f,dim=c(nfleets,nareas)) init.eff<-array(3,dim=c(nfleets,nareas)) OF<-array(c(q*f), dim=c(nfleets, nareas)) Catch<-array(0,dim=c(nfleets, nareas)) obj<-function(f){ f <- array(f, dim=c(nfleets, nareas)) F <- q*f Z <- M+sum(F) S <- exp(-Z) Catch<- N*F/Z*(1-S) Tot.Catch <- sum(Catch) NR<-array(0,dim=c(nfleets,nareas)) NR<-Price*Catch - f*cost d.NR<-array(0,dim=c(nfleets,nareas)) f <- apply(f, 1, sum) d.NR<- N*q/Z*(1-S-F/Z+F/Z*S+F*S)*Price - cost return(sum(d.NR*d.NR)) } zero.bnd <- rep.int(0, length(f)) opt.eff <- optim( init.eff, obj, method="Nelder-Mead" ) </code></pre>
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optimization in R across multiple 'areas'
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