length.bit: 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 bit
length(x)
# S3 method for bit
length(x) <- value
# S3 method for bitwhich
length(x)
# S3 method for bitwhich
length(x) <- value
# S3 method for ri
length(x)

Value

the length A bit vector with the new length

Arguments

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

Author

Jens Oehlschlägel

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.

Examples

Run this code


  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)

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