Package: bit
Type: Package
Title: A class for vectors of 1-bit booleans
Version: 1.1-1
Date: 2009-07-07
Author: Jens Oehlschl\xE4gel <Jens.Oehlschlaegel@truecluster.com>
Maintainer: Jens Oehlschl\xE4gel <Jens.Oehlschlaegel@truecluster.com>
Depends: R (>= 2.9.2)
Description: bitmapped vectors of booleans (no NAs), coercion from and
to logicals, integers and integer subscripts; fast boolean
operators and fast summary statistics. With 'bit' vectors you
can store true binary booleans {FALSE,TRUE} at the expense of 1
bit only, on a 32 bit architecture this means factor 32 less
RAM and factor 32 more speed on boolean operations. With this
speed gain it even pays-off to convert to bit in order to avoid
a single boolean operation on logicals or a single set
operation on (longer) integer subscripts, the pay-off is
dramatic when such components are used more than once. Reading
from and writing to bit is approximately as fast as accessing
standard logicals - mostly due to R's time for memory
allocation. The package allows to work with pre-allocated
memory for return values by calling .Call() directly: when
evaluating the speed of C-access with pre-allocated vector
memory, coping from bit to logical requires only 70% of the
time for copying from logical to logical; and copying from
logical to bit comes at a performance penalty of 150%. the
package now contains further classes for representing logical
selections: 'bitwhich' for very skewed selections and 'ri' for
selecting ranges of values for chunked processing. All three
index classes can be used for subsetting 'ff' objects (ff-2.1-0
and higher).
License: GPL-2
LazyLoad: yes
Encoding: latin1
Repository: CRAN
Repository/R-Forge/Project: ff
Repository/R-Forge/Revision: 8
Date/Publication: 2009-10-11 14:38:14
Packaged: 2009-10-09 20:11:04 UTC; rforge

Package: bit
Type: Package
Title: A class for vectors of 1-bit booleans
Version: 1.1-10
Date: 2012-01-17
Author: Jens Oehlschl�gel <Jens.Oehlschlaegel@truecluster.com>
Maintainer: Jens Oehlschl�gel <Jens.Oehlschlaegel@truecluster.com>
Depends: R (>= 2.9.2)
Description: bitmapped vectors of booleans (no NAs), coercion from and
to logicals, integers and integer subscripts; fast boolean
operators and fast summary statistics.  With 'bit' vectors you
can store true binary booleans {FALSE,TRUE} at the expense of 1
bit only, on a 32 bit architecture this means factor 32 less
RAM and ~ factor 32 more speed on boolean operations. Due to
overhead of R calls, actual speed gain depends on the size of
the vector: expect gains for vectors of size > 10000 elements.
Even for one-time boolean operations it can pay-off to convert
to bit, the pay-off is obvious, when such components are used
more than once.  Reading from and writing to bit is
approximately as fast as accessing standard logicals - mostly
due to R's time for memory allocation. The package allows to
work with pre-allocated memory for return values by calling
.Call() directly: when evaluating the speed of C-access with
pre-allocated vector memory, coping from bit to logical
requires only 70% of the time for copying from logical to
logical; and copying from logical to bit comes at a performance
penalty of 150%. the package now contains further classes for
representing logical selections: 'bitwhich' for very skewed
selections and 'ri' for selecting ranges of values for chunked
processing. All three index classes can be used for subsetting
'ff' objects (ff-2.1-0 and higher).
License: GPL-2
LazyLoad: yes
ByteCompile: yes
Encoding: latin1
URL: http://ff.r-forge.r-project.org/
Packaged: 2013-03-06 22:07:38 UTC; root
NeedsCompilation: yes
Repository: CRAN
Date/Publication: 2013-03-11 09:19:21