bit (version 1.1-15.1)

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

Arguments

x

a bit, bitwhich or ri object

value

the new number of bits

Value

the length A bit vector with the new length

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:

• TRUEall included, new bits are set to TRUE

• positive integerssome included, new bits are set to FALSE

• negative integerssome excluded, new bits are set to TRUE

• FALSEall 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.

See Also

length, sum, poslength, maxindex

Examples

# NOT RUN {
  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)
# }