Extensions of MPI_ SCATTER and MPI_SCATTERV

Description

mpi.scatter.Robj and mpi.scatter.Robj2slave are used to scatter a list to all members. They are more efficient than using any parallel apply functions.

Usage

mpi.scatter.Robj(obj = NULL, root = 0, comm = 1)
mpi.scatter.Robj2slave(obj, comm = 1)

Arguments

Details

mpi.scatter.Robj is an extension of mpi.scatter for scattering a list object from a sender (root) to everyone. mpi.scatter.Robj2slave scatters a list to all slaves.

Value

mpi.scatter.Robj for non-root members, returns the scattered R object. For the root member, it returns the portion belonging to itself. mpi.scatter.Robj2slave returns no value for the master and all slaves get their corresponding components in the list, i.e., the first slave gets the first component in the list.

Author(s)

Hao Yu and Wei Xia

See Also

mpi.scatter, mpi.gather.Robj,

Examples

#assume that there are three slaves running
mpi.bcast.cmd(x<-mpi.scatter.Robj())

xx <- list("master",rnorm(3),letters[2],1:10)
mpi.scatter.Robj(obj=xx)

mpi.remote.exec(x)

#scatter a matrix to slaves
dat=matrix(1:24,ncol=3)
splitmatrix = function(x, ncl) lapply(.splitIndices(nrow(x), ncl), function(i) x[i,])
dat2=splitmatrix(dat,3)
mpi.scatter.Robj2slave(dat2)
mpi.remote.exec(dat2)

Results

R version 3.3.1 (2016-06-21) -- "Bug in Your Hair"
Copyright (C) 2016 The R Foundation for Statistical Computing
Platform: x86_64-pc-linux-gnu (64-bit)

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> library(Rmpi)
Error in library(Rmpi) : there is no package called 'Rmpi'
Execution halted