Package: bit
Type: Package
Title: A class for vectors of 1-bit booleans
Version: 1.1.0
Date: 2009-07-07
Author: Jens Oehlschl�gel <Jens.Oehlschlaegel@truecluster.com>
Maintainer: Jens Oehlschl�gel <Jens.Oehlschlaegel@truecluster.com>
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
Packaged: 2009-07-23 20:00:38 UTC; Jens Oehlschlaegel
Repository: CRAN
Date/Publication: 2009-07-24 06:04:28

Title: Classes and Methods for Fast Memory-Efficient Boolean Selections
Author: Jens Oehlschlägel [aut, cre], Brian Ripley [ctb]
Suggests: testthat (>= 0.11.0), roxygen2, knitr, rmarkdown,
Description: Provided are classes for boolean and skewed boolean vectors,
fast boolean methods, fast unique and non-unique integer sorting,
fast set operations on sorted and unsorted sets of integers, and
foundations for ff (range index, compression, chunked processing).