describe, attach.big.matrix {bigmemory}R Documentation

The basic shared “big.matrix” operations.

Description

The attach.big.matrix creates a new big.matrix object which references shared memory which has previously been allocated.

The describe function returns the description needed by the attach.big.matrix function so that a newly created big.matrix instance can reference a previously allocated shared memory instance of type big.matrix.

Usage

describe(x)
attach.big.matrix(obj)

Arguments

x a shared big.matrix.
obj an object as returned by describe().

Details

After a shared big.matrix instance is created, the describe function can be called to retrieve the keys which refer to the shared memory locations which the instance manages. These keys are then used for a new shared big.matrix instance to refer to the same memory across R sessions.

Value

describe returns a list of shared memory keys as well as column and row names.
attach.big.matrix return a new instance of type big.matrix which refers to the shared memory described by the describe function.

Author(s)

John W. Emerson and Michael J. Kane

See Also

bigmemory, big.matrix, or the class documentation big.matrix.

Examples

# This example won't run on the Windows version of the package,
# and if you are reading this message you are most certainly using
# a non-Windows version.

# The example is quite silly, as you wouldn't likely do this in a
# single R session.  But if zdescription were passed to another R session
# via SNOW, NetWorkSpaces, or even by a simple file read/write,
# then the attach of the second R process would give access to the
# same object in memory.  Please see the package vignette for real examples.
## Not run: 
z <- shared.big.matrix(3, 3, type='integer', init=3)
z[,]
dim(z)
z[1,1] <- 2
z[,]
zdescription <- describe(z)
zdescription
y <- attach.big.matrix(zdescription)
y[,]
y
z
y[1,1] <- -100
y[,]
z[,]
## End(Not run)

[Package bigmemory version 2.3 Index]