Use case: interactive cluster computing from RStudio.
There are many ways to parallelize R, both for interactive and batch-style computation. The approach shown in this document uses the parallel package and RStudio on Amazon EC2.
For map/reduce style computations, look at Rhipe or Segue. For batch jobs, Starcluster is likely may be a better choice. Brian Holt (Unlicensed) wrote up a document on using R in on starcluster called /wiki/spaces/IT/pages/7867417. Other documents give an overview of Distributed Computation Strategy and how to run Distributed Compute Jobs.
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