Extentions of MPI_Gather and MPI_Allgather APIs

Description

mpi.gather.Robj gathers each member's object to the member specified by the argument root. The root member receives the objects as a list. mpi.allgather.Robj is the same as mpi.gather.Robj except that all members receive the result instead of just the root.

Usage

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

mpi.allgather.Robj(obj=NULL, comm = 1)

Arguments

Details

Since sapply is used to gather all results, its default option "simplify=TRUE" is to simplify outputs. In some situations, this option is not desirable. Using "simplify=FALSE" as in the place of ... will tell sapply not to simplify and a list of outputs will be returned.

Value

For mpi.gather.Robj, it returns a list, the gathered message for the root member. For mpi.allgatherv.Robj, it returns a list, the gathered message for all members.

Author(s)

Hao Yu and Wei Xia

References

http://www.lam-mpi.org/, http://www-unix.mcs.anl.gov/mpi/www/www3/

See Also

mpi.gather, mpi.allgatherv.

Examples

#Assume that there are some slaves running
mpi.bcast.cmd(id<-mpi.comm.rank())
mpi.bcast.cmd(x<-rnorm(id))
mpi.bcast.cmd(mpi.gather.Robj(x))
x<-"test mpi.gather.Robj"
mpi.gather.Robj(x)

mpi.bcast.cmd(obj<-rnorm(id+10))
mpi.bcast.cmd(nn<-mpi.allgather.Robj(obj))
obj<-rnorm(5)
mpi.allgather.Robj(obj)
mpi.remote.exec(nn)

Results

R version 3.3.1 (2016-06-21) -- "Bug in Your Hair"
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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