Bug ID: 1553054
           Summary: Review Request: R-bit - A class for vectors of 1-bit
           Product: Fedora
           Version: rawhide
         Component: Package Review
        QA Contact:

Spec URL:

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).

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