# bit v1.1-14

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## A Class for Vectors of 1-Bit Booleans

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).

## Functions in bit

Name | Description | |

c.bit | Concatenating bit and bitwhich vectors | |

unattr | Attribute removal | |

vecseq | Vectorized Sequences | |

setattributes | Attribute setting by reference | |

rlepack | Hybrid Index, rle-pack utilities | |

regtest.bit | Regressiontests for bit | |

repeat.time | Adaptive timer | |

repfromto | Virtual recycling | |

ri | Range index | |

as.which | Coercion to (positive) integer positions | |

Extract | Extract or replace part of an bit vector | |

Summary | Summaries of bit vectors | |

as.bit | Coercing to bit | |

bbatch | Balanced Batch sizes | |

bit_init | Initializing bit masks | |

as.logical.bit | Coercion from bit, bitwhich and ri to logical, integer, double | |

as.bitwhich | Coercing to bitwhich | |

physical | Physical and virtual attributes | |

bit-package | A class for vectors of 1-bit booleans | |

is.bit | Testing for bit, bitwhich and ri selection classes | |

clone | Cloning ff and ram objects | |

chunk | Chunked range index | |

intrle | Hybrid Index, C-coded utilities | |

ramsort | Generics for in-RAM sorting and ordering | |

LogicBit | Boolean operators and functions for class bit | |

is.sorted | Generics related to cache access | |

length.bit | Getting and setting length of bit, bitwhich and ri objects | |

bitwhich | A class for vectors representing asymetric selections | |

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## Last month downloads

## Details

Type | Package |

Date | 2018-04-11 |

License | GPL-2 |

LazyLoad | yes |

ByteCompile | yes |

Encoding | UTF-8 |

URL | http://ff.r-forge.r-project.org/ |

NeedsCompilation | yes |

Packaged | 2018-05-27 20:28:22 UTC; jens |

Repository | CRAN |

Date/Publication | 2018-05-29 16:56:33 UTC |

depends | R (>= 2.9.2) |

Contributors | Jens Oehlschl�gel |

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