[R] multicore package: help

[Patrick Connolly]

On Mon, 01-Nov-2010 at 06:10PM -0400, Fahim M wrote:

|> I have matrices as below:
|> 
|> a <- matrix(c(1:10, 11, 12), 3,4)
|> aa <- data.frame(a)
|> 
|> b <- matrix(c(10:20, 21), 4,3)
|> bb <- data.frame(b)
|> ...
|> and many more matrices.
|> 
|> st = list(aa,bb, ..... )

There's probably a tidier way to do it, but without knowing what sort
of thing you want to do, I probably don't have the best way of doing
it, but the following should help you.

You don't need a list in this case.  A simple vector will suffice.
 
st <- c("aa", "bb", etc...)


|> 
|> mclapply(st, FUN, mc.cores=6); #this function apply the function to the
|> elements of the list 'aa', 'bb'...etc
|> 
|> 
|> FUN = function(st)

Use something different from st.  Whatever you call it will be the
individual values.

FUN <- function(x){
ind <- which(st == x) # which is the index you want.
mat.x <- get(x) # which will be the dataframe for that part of your list.

... etc...

}

then assign the output of mclapply to a list

out.list <-  mclapply(st, FUN, mc.cores=6)

You'll probably find it useful to name its elements like this:

names(out.list) <- st




HTH




|>  {
|>  Is there a way/function to know the index of st(the list) currently
|> processed by this function as these matrices  are processed in the order of
|> availability of processors?
|> for example, if matrix bb is being processed then the index that I want is
|> 2.
|>  ...
|>  ...
|>  ...
|> 
|>  }
|> 
|> 	[[alternative HTML version deleted]]
|> 
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|> and provide commented, minimal, self-contained, reproducible code.

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   ___    Patrick Connolly   
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