Package: bit
Type: Package
Title: A class for vectors of 1-bit booleans
Version: 1.1-3
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. 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
URL: http://ff.r-forge.r-project.org/
Encoding: latin1
Repository: CRAN
Repository/R-Forge/Project: ff
Repository/R-Forge/Revision: 34
Date/Publication: 2010-01-20 13:10:56
Packaged: 2009-12-30 21:08:15 UTC; rforge

Package: bit
Type: Package
Title: A class for vectors of 1-bit booleans
Version: 1.1-4
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. 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
URL: http://ff.r-forge.r-project.org/
Encoding: latin1
Repository: CRAN
Repository/R-Forge/Project: ff
Repository/R-Forge/Revision: 42
Date/Publication: 2010-03-23 07:26:51
Packaged: 2010-03-21 21:38:42 UTC; rforge