sub.big.matrix: Submatrix support

In bigmemory: Manage Massive Matrices with Shared Memory and Memory-Mapped Files

Submatrix support

Description

This doesn't create a copy, it just provides a new version of the class which provides behavior for a contiguous submatrix of the big.matrix. Non-contiguous submatrices are not supported.

Usage

is.sub.big.matrix(x)

## S4 method for signature 'big.matrix'
is.sub.big.matrix(x)

sub.big.matrix(
  x,
  firstRow = 1,
  lastRow = NULL,
  firstCol = 1,
  lastCol = NULL,
  backingpath = NULL
)

## S4 method for signature 'big.matrix'
sub.big.matrix(
  x,
  firstRow = 1,
  lastRow = NULL,
  firstCol = 1,
  lastCol = NULL,
  backingpath = NULL
)

## S4 method for signature 'big.matrix.descriptor'
sub.big.matrix(
  x,
  firstRow = 1,
  lastRow = NULL,
  firstCol = 1,
  lastCol = NULL,
  backingpath = NULL
)

Arguments

x	A descriptor object
firstRow	the first row of the submatrix
lastRow	the last row of the submatrix if not NULL
firstCol	the first column of the submatrix
lastCol	of the submatrix if not NULL
backingpath	required path to the filebacked object, if applicable

Details

The sub.big.matrix function allows a user to create a big.matrix object that references a contiguous set of columns and rows of another big.matrix object.

The is.sub.big.matrix function returns TRUE if the specified argument is a sub.big.matrix object and return FALSE otherwise.

Value

A big.matrix which is actually a submatrix of a larger big.matrix. It is not a physical copy. Only contiguous blocks may form a submatrix.

Author(s)

John W. Emerson and Michael J. Kane

See Also

big.matrix

Examples

x <- big.matrix(10, 5, init=0, type="double")
x[,] <- 1:50
y <- sub.big.matrix(x, 2, 9, 2, 3)
y[,]
y[1,1] <- -99
x[,]
rm(x)

bigmemory documentation built on May 29, 2024, 12:18 p.m.