Produces a physical copy of a “big.matrix”

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Description

This is needed to make a duplicate of a big.matrix, with the new copy optionally filebacked.

Usage

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deepcopy(x, cols = NULL, rows = NULL, y = NULL, type = NULL, 
  separated = NULL, backingfile = NULL, backingpath = NULL,
  descriptorfile = NULL, binarydescriptor=FALSE, shared=TRUE)

Arguments

x

a big.matrix.

cols

possible subset of columns for the deepcopy; could be numeric, named, or logical.

rows

possible subset of rows for the deepcopy; could be numeric, named, or logical.

y

optional destination object (matrix or big.matrix); if not specified, a big.matrix will be created.

type

preferably specified, "integer" for example.

separated

use separated column organization of the data instead of column-major organization; use with caution if the number of columns is large.

backingfile

the root name for the file(s) for the cache of x.

backingpath

the path to the directory containing the file-backing cache.

descriptorfile

we recommend specifying this for file-backing.

binarydescriptor

the flag to specify if the binary RDS format should be used for the backingfile description, for subsequent use with attach.big.matrix; if NULL of FALSE, the dput() file format is used.

shared

TRUE by default, and always TRUE if the big.matrix is file-backed. For a non-filebacked big.matrix, shared=FALSE uses non-shared memory, which can be more stable for large (say, >50% of RAM) objects. Shared memory allocation can sometimes fail in such cases due to exhausted shared-memory resources in the system.

Details

This is needed to make a duplicate of a big.matrix, because traditional R syntax would only copy the R object (the pointer to the big.matrix rather than the big.matrix itself). It can also make a copy of only a subset of columns.

Value

a big.matrix.

See Also

big.matrix

Examples

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x <- as.big.matrix(matrix(1:30, 10, 3))
y <- deepcopy(x, -1)    # Don't include the first column.
x
y
head(x)
head(y)