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

In bit: Classes and Methods for Fast Memory-Efficient Boolean Selections

Getting and setting length of bit, bitwhich and ri objects

Description

Query the number of bits in a bit vector or change the number of bits in a bit vector.
Query the number of bits in a bitwhich vector or change the number of bits in a bit vector.

Usage

## S3 method for class 'bit'
length(x)

## S3 replacement method for class 'bit'
length(x) <- value

## S3 method for class 'bitwhich'
length(x)

## S3 replacement method for class 'bitwhich'
length(x) <- value

## S3 method for class 'ri'
length(x)

Arguments

x	a bit, bitwhich or ri object
value	the new number of bits

Details

NOTE that the length does NOT reflect the number of selected (TRUE) bits, it reflects the sum of both, TRUE and FALSE bits. Increasing the length of a bit object will set new bits to FALSE. The behaviour of increasing the length of a bitwhich object is different and depends on the content of the object:

• TRUE – all included, new bits are set to TRUE

• positive integers – some included, new bits are set to FALSE

• negative integers – some excluded, new bits are set to TRUE

• FALSE – all excluded:, new bits are set to FALSE

Decreasing the length of bit or bitwhich removes any previous information about the status bits above the new length.

Value

the length A bit vector with the new length

Author(s)

Jens Oehlschlägel

See Also

length, sum, poslength, maxindex

Examples

  stopifnot(length(ri(1, 1, 32))==32)

  x <- as.bit(ri(32, 32, 32))
  stopifnot(length(x)==32)
  stopifnot(sum(x)==1)
  length(x) <- 16
  stopifnot(length(x)==16)
  stopifnot(sum(x)==0)
  length(x) <- 32
  stopifnot(length(x)==32)
  stopifnot(sum(x)==0)

  x <- as.bit(ri(1, 1, 32))
  stopifnot(length(x)==32)
  stopifnot(sum(x)==1)
  length(x) <- 16
  stopifnot(length(x)==16)
  stopifnot(sum(x)==1)
  length(x) <- 32
  stopifnot(length(x)==32)
  stopifnot(sum(x)==1)

  x <- as.bitwhich(bit(32))
  stopifnot(length(x)==32)
  stopifnot(sum(x)==0)
  length(x) <- 16
  stopifnot(length(x)==16)
  stopifnot(sum(x)==0)
  length(x) <- 32
  stopifnot(length(x)==32)
  stopifnot(sum(x)==0)

  x <- as.bitwhich(!bit(32))
  stopifnot(length(x)==32)
  stopifnot(sum(x)==32)
  length(x) <- 16
  stopifnot(length(x)==16)
  stopifnot(sum(x)==16)
  length(x) <- 32
  stopifnot(length(x)==32)
  stopifnot(sum(x)==32)

  x <- as.bitwhich(ri(32, 32, 32))
  stopifnot(length(x)==32)
  stopifnot(sum(x)==1)
  length(x) <- 16
  stopifnot(length(x)==16)
  stopifnot(sum(x)==0)
  length(x) <- 32
  stopifnot(length(x)==32)
  stopifnot(sum(x)==0)

  x <- as.bitwhich(ri(2, 32, 32))
  stopifnot(length(x)==32)
  stopifnot(sum(x)==31)
  length(x) <- 16
  stopifnot(length(x)==16)
  stopifnot(sum(x)==15)
  length(x) <- 32
  stopifnot(length(x)==32)
  stopifnot(sum(x)==31)

  x <- as.bitwhich(ri(1, 1, 32))
  stopifnot(length(x)==32)
  stopifnot(sum(x)==1)
  length(x) <- 16
  stopifnot(length(x)==16)
  stopifnot(sum(x)==1)
  length(x) <- 32
  stopifnot(length(x)==32)
  stopifnot(sum(x)==1)

  x <- as.bitwhich(ri(1, 31, 32))
  stopifnot(length(x)==32)
  stopifnot(sum(x)==31)
  message("NOTE the change from 'some excluded' to 'all excluded' here")
  length(x) <- 16
  stopifnot(length(x)==16)
  stopifnot(sum(x)==16)
  length(x) <- 32
  stopifnot(length(x)==32)
  stopifnot(sum(x)==32)

bit documentation built on Sept. 20, 2024, 5:08 p.m.