Compare the snow and foreach approaches to parallel processing in R on three practical examples, starting with k-means clustering on the Boston data.

Loop in parallel on one machine in R with the foreach and doParallel packages, with the iterators package covered for writing the loop itself.

Run parallel tasks on one machine in R with the snow and parallel packages, comparing clusterApply, clusterApplyLB, parLapply and parLapplyLB.