Save results of foreach loop in a matrix

I am trying to adapt a for loop to use it in parallel as a foreach loop. For the for loop I create an empty matrix then fill it with the values generated by the for loop. But this approach doesn't work in the foreach loop,

results<-matrix(nrow=length(classes),ncol=length(files))
dimnames(results)[[1]]<-classes
dimnames(results)[[2]]<-files

ptime<-system.time({
    foreach(z = 1:length(files),.packages="raster") %dopar% {
      raster <- raster(paste(folder,files[z],sep=""))
      data<-getValues(raster)
      clp <- na.omit(data)
      for(i in 1:length(classes)){
        results[i,z]<-length(clp[clp==classes[i]])/length(clp)
        print(z)
      }
    }
})

My results matrix is still just filled with na's, it doesn't get populated.

z is a raster file, i is a vector of numerical classes. I want the number of cells in raster z for each class i, and then divide this by the total number of cells in raster z to get this as a proportion.

Any advice on how I can save this as a matrix/dataframe in a foreach loop?

Thank you in advance.

Follow up of this previous question