vv_print_cat: Global Print and Cat Functions
In pbdMPI: R Interface to MPI for HPC Clusters (Programming with Big Data Project)

global print and cat

R Documentation

Global Print and Cat Functions

Description

The functions globally print or cat a variable from specified processors, by default messages is shown on screen.

Usage

comm.print(x, all.rank = .pbd_env$SPMD.CT$print.all.rank,
           rank.print = .pbd_env$SPMD.CT$rank.source,
           comm = .pbd_env$SPMD.CT$comm,
           quiet = .pbd_env$SPMD.CT$print.quiet,
           flush = .pbd_env$SPMD.CT$msg.flush,
           barrier = .pbd_env$SPMD.CT$msg.barrier,
           con = stdout(), sleep = 0, ...)

comm.cat(..., all.rank = .pbd_env$SPMD.CT$print.all.rank,
         rank.print = .pbd_env$SPMD.CT$rank.source,
         comm = .pbd_env$SPMD.CT$comm,
         quiet = .pbd_env$SPMD.CT$print.quiet, sep = " ", fill = FALSE,
         labels = NULL, append = FALSE, flush = .pbd_env$SPMD.CT$msg.flush,
         barrier = .pbd_env$SPMD.CT$msg.barrier, con = stdout(), sleep = 0)

Arguments

`x`	a variable to be printed.
`...`	variables to be cat.
`all.rank`	if all ranks print (default = FALSE).
`rank.print`	rank for printing if not all ranks print (default = 0).
`comm`	communicator for printing (default = 1).
`quiet`	Logical to control whether whether a "COMM.RANK = #" line is added to indicate which rank is printing, or integer to do rank-coloring instead. If integer, giving a communicator number, up to 8 colors are used to distinguish each rank prints. If the specified communicator has more than 8 ranks, colors are recycled. With a single communicator, this is straightforward. This can be extremely helpful in debugging complex communicator splits. In these cases, the parameter 'comm' below can be different from the split communicator assigned to 'quiet'.
`sep`	sep argument as in the `cat()` function.
`fill`	fill argument as in the `cat()` function.
`labels`	labels argument as in the `cat()` function.
`append`	labels argument as in the `cat()` function.
`flush`	if flush `con`.
`barrier`	if barrier `con`.
`con`	`stdout()` is the default to print message.
`sleep`	Normally left at 0. If overprinting by ranks occurrs, set to 0.01 or smaller to delay the first printing rank action and allow any previous print to land.

Details

Warning: These two functions use barrier() to make sure the well printing process on screen, so should be called by all processors to avoid a deadlock. A typical misuse is called inside a condition check, such as if(.comm.rank == 0) comm.cat(...).

rank.print can be a integer vector containing the ranks of processors which print messages.

Value

A print() or cat() is called for the specified processors and the messages of the input variables is shown on screen by default.

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: https://pbdr.org/

Examples

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

spmd.code <- "
### Initialize
suppressMessages(library(pbdMPI, quietly = TRUE))

### Example.
comm.print(comm.rank(), rank.print = 1)

### Finish.
finalize()
"
# execmpi(spmd.code, nranks = 2L)

## End(Not run)

pbdMPI documentation built on Aug. 30, 2025, 1:12 a.m.