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Module Version: 0.27   Source   Latest Release: Statistics-R-0.34

NAME

Statistics::R - Perl interface with the R statistical program

DESCRIPTION

Statistics::R is a module to controls the R interpreter (R project for statistical computing: http://www.r-project.org/). It lets you start R, pass commands to it and retrieve the output. A shared mode allow to have several instances of Statistics::R talk to the same R process.

The current Statistics::R implementation uses pipes (for stdin, stdout and and stderr) to communicate with R. This implementation should be more efficient and reliable than that in previous version, which relied on reading and writing files. As before, this module works on GNU/Linux, MS Windows and probably many more systems.

SYNOPSIS

```  use Statistics::R;

# Create a communication bridge with R and start R
my \$R = Statistics::R->new();

# Run simple R commands
my \$output_file = "file.ps";
\$R->run(qq`postscript("\$output_file" , horizontal=FALSE , width=500 , height=500 , pointsize=1)`);
\$R->run(q`plot(c(1, 5, 10), type = "l")`);
\$R->run(q`dev.off()`);

# Pass and retrieve data (scalars or arrays)
my \$input_value = 1;
\$R->set('x', \$input_value);
\$R->run(q`y <- x^2`);
my \$output_value = \$R->get('y');
print "y = \$output_value\n";

\$R->stop();```

METHODS

new()

Build a Statistics::R bridge object between Perl and R. Available options are:

r_bin

Specify the full path to R if it is not automatically found. See INSTALLATION.

shared

Start a shared bridge. When using a shared bridge, several instances of Statistics::R can communicate with the same unique R instance. Example:

```   use Statistics::R;

my \$R1 = Statistics::R->new( shared => 1);
my \$R2 = Statistics::R->new( shared => 1);

\$R1->set( 'x', 'pear' );
my \$x = \$R2->get( 'x' );
print "x = \$x\n";```

Do not call the stop() method is you still have processes that need to interact with R.

run()

First, start() R if it is not yet running. Then, execute R commands passed as a string and return the output as a string. If your command fails to run in R, an error message will be displayed.

Example:

`   my \$out = \$R->run( q`print( 1 + 2 )` );`

If you intend on runnning many R commands, it may be convenient to pass an array of commands or put multiple commands in an here-doc:

```   # Array of R commands:
my \$out1 = \$R->run(
q`a <- 2`,
q`b <- 5`,
q`c <- a * b`,
q`print("ok")`
);

# Here-doc with multiple R commands:
my \$cmds = <<EOF;
a <- 2
b <- 5
c <- a * b
print('ok')
EOF
my \$out2 = \$R->run(\$cmds);```

To run commands from a file, see the run_from_file() method.

The output you get from run() is the combination of what R would display on the standard output and the standard error, but the order may differ. When loading modules, some may write numerous messages on standard error. You can disable this behavior using the following R command:

`   suppressPackageStartupMessages(library(library_to_load))`

Note that R imposes an upper limit on how many characters can be contained on a line: about 4076 bytes maximum. You will be warned if this occurs. Commands containing lines exceeding the limit may fail with an error message stating:

`  '\�' is an unrecognized escape in character string starting "...`

If possible, break down your R code into several smaller, more manageable statements. Alternatively, adding newline characters "\n" at strategic places in the R statements will work around the issue.

run_from_file()

Similar to run() but reads the R commands from the specified file. Internally, this method uses the R source() command to read the file.

set()

Set the value of an R variable (scalar or arrayref). Example:

`  \$R->set( 'x', 'pear' );`

or

`  \$R->set( 'y', [1, 2, 3] );`
get()

Get the value of an R variable (scalar or arrayref). Example:

`  my \$x = \$R->get( 'x' );  # \$y is a scalar`

or

`  my \$y = \$R->get( 'y' );  # \$x is an arrayref`
start()

Explicitly start R. Most times, you do not need to do that because the first execution of run() or set() will automatically call start().

stop()

Stop a running instance of R.

restart()

stop() and start() R.

bin()

Get or set the path to the R executable.

is_shared()

Was R started in shared mode?

is_started()

Is R running?

pid()

Return the pid of the running R process

INSTALLATION

Since Statistics::R relies on R to work, you need to install R first. See this page for downloads, http://www.r-project.org/. If R is in your PATH environment variable, then it should be available from a terminal and be detected automatically by Statistics::R. This means that you don't have to do anything on Linux systems to get Statistics::R working. On Windows systems, in addition to the folders described in PATH, the usual suspects will be checked for the presence of the R binary, e.g. C:\Program Files\R. If Statistics::R does not find R installation, your last recourse is to specify its full path when calling new():

`    my \$R = Statistics::R->new( r_bin => \$fullpath );`

You also need to have the following CPAN Perl modules installed:

IPC::Run
Regexp::Common
Text::Balanced (>= 1.97)

AUTHORS

Florent Angly <florent.angly@gmail.com> (2011 rewrite)

Graciliano M. P. <gm@virtuasites.com.br> (original code)

MAINTAINER

Brian Cassidy <bricas@cpan.org>

`   git clone git://github.com/bricas/statistics-r.git`