mpi.apply {Rmpi}

Scatter an array to slaves and then apply a FUN

Description

An array (length <= total number of slaves) is scattered to slaves so that the first slave calls FUN with arguments x[[1]] and ..., the second one calls with arguments x[[2]] and ..., and so on. mpi.iapply is a nonblocking version of mpi.apply so that it will not consume CPU on master node.

Usage

mpi.apply(X, FUN, ..., comm=1)  
mpi.iapply(X, FUN, ..., comm=1, sleep=0.01)  

Arguments

X

an array

FUN

a function

...

optional arguments to FUN

comm

a communicator number

sleep

a sleep interval on master node (in sec)

Value

A list of the results is returned. Its length is the same as that of x. In case the call FUN with arguments x[[i]] and ... fails on ith slave, corresponding error message will be returned in the returning list.

Author(s)

Hao Yu

Examples

#Assume that there are at least 5 slaves running
#Otherwise run mpi.spawn.Rslaves(nslaves=5)
#x=c(10,20)
#mpi.apply(x,runif)
#meanx=1:5
#mpi.apply(meanx,rnorm,n=2,sd=4)