inst/examples/test_spmd/reduce.r

In RBigData/pbdMPI: R Interface to MPI for HPC Clusters (Programming with Big Data Project)

### SHELL> mpiexec -np 2 Rscript --vanilla [...].r

suppressMessages(library(pbdMPI, quietly = TRUE))
.comm.size <- comm.size()
.comm.rank <- comm.rank()

N <- 5
x <- (1:N) + N * .comm.rank
y <- reduce(matrix(as.integer(x), nrow = 1), op = "sum")
comm.print(y)
y <- reduce(matrix(as.double(x), nrow = 1), op = "sum")
comm.print(y)

y <- reduce(as.integer(x), op = "sum")
comm.print(y)
y <- reduce(as.double(x), op = "sum")
comm.print(y)

y <- reduce(as.integer(x), op = "prod")
comm.print(y)
y <- reduce(as.double(x), op = "prod")
comm.print(y)

y <- reduce(as.integer(x), op = "max")
comm.print(y)
y <- reduce(as.double(x), op = "max")
comm.print(y)

y <- reduce(as.integer(x), op = "min")
comm.print(y)
y <- reduce(as.double(x), op = "min")
comm.print(y)

comm.cat("\n-- Print from rank 1:\n", rank.print = 1, quiet = TRUE)
comm.print(y, rank.print = 1)

finalize()