Package: bit
Title: A Class for Vectors of 1-Bit Booleans
Version: 1.1-15
Date: 2020-01-12
Authors@R: c(person("Jens", "Oehlschlägel", role = c('aut', 'cre'),
email = "Jens.Oehlschlaegel@truecluster.com"),
person("Brian", "Ripley", role = 'ctb'))
Depends: R (>= 2.9.2)
Description: True boolean datatype (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: UTF-8
NeedsCompilation: yes
Packaged: 2020-01-13 08:46:07 UTC; ripley
Author: Jens Oehlschlägel [aut, cre],
Brian Ripley [ctb]
Maintainer: Jens Oehlschlägel <Jens.Oehlschlaegel@truecluster.com>
Repository: CRAN
Date/Publication: 2020-01-13 08:47:57 UTC

Package: bit
Type: Package
Title: A class for vectors of 1-bit booleans
Version: 1.1-2
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
URL: http://ff.r-forge.r-project.org/
Encoding: latin1
Repository: CRAN
Repository/R-Forge/Project: ff
Repository/R-Forge/Revision: 16
Date/Publication: 2009-10-26 19:26:39
Packaged: 2009-10-25 21:08:26 UTC; rforge