./devel/R-bit, Class for vectors of 1-bit booleans

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Branch: CURRENT, Version: 1.1.12, Package name: R-bit-1.1.12, Maintainer: minskim

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).


Required to run:
[math/R]

Required to build:
[pkgtools/cwrappers]

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   2018-03-06 18:06:28 by Min Sik Kim | Files touched by this commit (3)
Log message:
devel/R-bit: Import version 1.1.12

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).