Global Which Functions

Description

These functions are global which, which.max and which.min applying on distributed data for all ranks.

Usage

comm.which(x, arr.ind = FALSE, useNames = TRUE,
           comm = .pbd_env$SPMD.CT$comm)
comm.which.max(x, comm = .pbd_env$SPMD.CT$comm)
comm.which.min(x, comm = .pbd_env$SPMD.CT$comm)

Arguments

Details

These functions will apply which(), which.max() and which.min() locally, and apply allgather() to get all local results from other ranks.

Value

The global values (which(), which.max(), or which.min()) are returned to all ranks.

comm.which() returns with two columns, 'rank id' and 'index of TRUE'.

comm.which.max() and comm.which.min() return with three values, 'the _smallest_ rank id', 'index of the _first_ maximum or minimum', and 'max/min value of x'.

Author(s)

Wei-Chen Chen wccsnow@gmail.com, George Ostrouchov, Drew Schmidt, Pragneshkumar Patel, and Hao Yu.

References

Programming with Big Data in R Website: http://r-pbd.org/

See Also

comm.read.table()

Examples

## Not run: 
### Save code in a file "demo.r" and run with 2 processors by
### SHELL> mpiexec -np 2 Rscript demo.r

### Initial.
suppressMessages(library(pbdMPI, quietly = TRUE))
init()
if(comm.size() != 2){
  comm.cat("2 processors are requried.\n", quiet = TRUE)
  finalize()
}

### Examples.
a <- 1:(comm.rank() + 1)

b <- comm.which(a == 2)
comm.print(b)
b <- comm.which.max(a)
comm.print(b)
b <- comm.which.min(a)
comm.print(b)

### Finish.
finalize()

## End(Not run)