How can I use foreach with snow, to allow multicore on windows XP (in R).

Question

could you please give an example on how that might be done using the doSNOW ?

(I asked the same question here: http://blog.revolution-computing.com/2009/08/parallel-programming-with-foreach-and-snow.html And got only a partial reply)

Tal

Answer 1

I fear that you are getting a few things muddled up and confused, as you did in your recent post on the r-help list:

1. Think about it from the bottom up.
2. You need a mechanism for parallel computing, whether or not it involves several machines.
3. The snow package does that for you, which is one of the reasons we highlighted it in the JSS survey paper
4. You can start with snow, which in the simplest case works a) on Windows and b) does not require MPI or PVM -- just use sockets
5. Once you have that figured out, move 'up' to higher levels of abstraction of using snow with the doSNOW backend to support foreach.
6. The multicore package does not (yet?) work on Windows and is of no (current?) use to you, so ignore it at least for now. Likewise for its doMC backend.

Working examples exist for each step along the way. I always fall back to verifying by test cases what works and what doesn't.