bigmemory (version 4.6.4)

describe,big.matrix-method: The basic ``big.matrix'' operations for sharing and re-attaching.

Description

The describe function returns the information needed by attach.big.matrix to reference a shared or file-backed big.matrix object. The attach.big.matrix and attach.resource functions create a new big.matrix object based on the descriptor information referencing previously allocated shared-memory or file-backed matrices.

Usage

# S4 method for big.matrix
describe(x)
attach.big.matrix(obj, ...)

Value

describe returns a list of of the information needed to attach to a big.matrix object.

attach.big.matrix return a new instance of type big.matrix

corresponding to a shared-memory or file-backed big.matrix.

Arguments

x

a big.matrix object

obj

an object as returned by describe() or, optionally, the filename of the descriptor for a filebacked matrix, assumed to be in the directory specified by the path (if one is provided)

...

possibly path which gives the path where the descriptor and/or filebacking can be found

Author

Michael J. Kane and John W. Emerson

Details

The describe function returns a list of the information needed to attach to a big.matrix object. A descriptor file is automatically created when a new filebacked big.matrix is created.

See Also

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

Examples

# 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, foreach, 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.

z <- 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
zz <- attach.resource(zdescription)
zz[1,1] <- -100
y[,]
z[,]