bit (1.1-10)
A class for vectors of 1-bit booleans.
http://ff.r-forge.r-project.org/
http://cran.r-project.org/web/packages/bit
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).
Maintainer:
Jens Oehlschlägel
Author(s): Jens Oehlschlägel <Jens.Oehlschlaegel@truecluster.com>
License: GPL-2
Uses: Does not use any package
Reverse depends: eigendog, ff, ffbase, MSBVAR
Reverse suggests: Stack
Released 2 months ago.
10 previous versions
- bit_1.1-9. Released 7 months ago.
- bit_1.1-8. Released over 1 year ago.
- bit_1.1-7. Released about 2 years ago.
- bit_1.1-6. Released over 2 years ago.
- bit_1.1-4. Released about 3 years ago.
- bit_1.1-3. Released over 3 years ago.
- bit_1.1-2. Released over 3 years ago.
- bit_1.1-1. Released over 3 years ago.
- bit_1.1.0. Released almost 4 years ago.
- bit_1.0-2. Released over 4 years ago.
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