pbdDMAT (version 0.4-2)

ddmatrix-apply: Apply Family of Functions

Description

Apply a function to the margins of a distributed matrix.

Usage

# S4 method for ddmatrix
apply(X, MARGIN, FUN, ..., reduce = FALSE,
  proc.dest = "all")

Arguments

X

distributed matrix

MARGIN

subscript over which the function will be applied

FUN

the function to be applied

...

additional arguments to FUN

reduce

logical or string. See details

proc.dest

Destination process (or 'all') if a reduction occurs

Value

Returns a distributed matrix unless a reduction is requested, then a global matrix/vector is returned.

Details

If reduce==TRUE then a global matrix or vector (whichever is more appropriate) will be returned. The argument proc.dest= behaves exactly as in the as.vector() and as.matrix() functions of pbdDMAT. If reduce=FALSE then a distributed matrix is returned. Other acceptable arguments are reduce="matrix" and reduce="vector" which demand global matrix or vector return, respectively. This should generally be slightly more efficient than running apply and then calling as.vector() or as.matrix().

Examples

# NOT RUN {
# Save code in a file "demo.r" and run with 2 processors by
# > mpiexec -np 2 Rscript demo.r

library(pbdDMAT, quiet = TRUE)
init.grid()

x <- ddmatrix(1:9, 3, bldim=2)

y <- as.vector(apply(x, 1, mean))
comm.print(y)

finalize()
# }
# NOT RUN {
# }