is.sub.big.matrix {bigmemory} R Documentation

## 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
)


### Arguments

 x either a big.matrix or a descriptor. 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 the last column 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

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)


[Package bigmemory version 4.6.1 Index]