bit (version 1.1-14)

Summary: Summaries of bit vectors

Description

Fast aggregation functions for bit vectors.

Usage

# S3 method for bit
all(x, range = NULL, …)
# S3 method for bit
any(x, range = NULL, …)
# S3 method for bit
min(x, range = NULL, …)
# S3 method for bit
max(x, range = NULL, …)
# S3 method for bit
range(x, range = NULL, …)
# S3 method for bit
sum(x, range = NULL, …)
# S3 method for bit
summary(object, range = NULL, …)
# S3 method for bitwhich
all(x, …)
# S3 method for bitwhich
any(x, …)
# S3 method for bitwhich
min(x, …)
# S3 method for bitwhich
max(x, …)
# S3 method for bitwhich
range(x, …)
# S3 method for bitwhich
sum(x, …)
# S3 method for bitwhich
summary(object, …)
# S3 method for ri
all(x, …)
# S3 method for ri
any(x, …)
# S3 method for ri
min(x, …)
# S3 method for ri
max(x, …)
# S3 method for ri
range(x, …)
# S3 method for ri
sum(x, …)
# S3 method for ri
summary(object, …)

Arguments

x

an object of class bit or bitwhich

object

an object of class bit

range

a ri or an integer vector of length==2 giving a range restriction for chunked processing

…

formally required but not used

Value

as expected

Details

Bit summaries are quite fast because we use a double loop that fixes each word in a processor register. Furthermore we break out of looping as soon as possible.

See Also

bit, all, any, min, max, range, sum, summary

Examples

# NOT RUN {
  x <- as.bit(c(TRUE, TRUE))
  all(x)
  any(x)
  min(x)
  max(x)
  range(x)
  sum(x)
  summary(x)

  x <- as.bitwhich(c(TRUE, TRUE))
  all(x)
  any(x)
  min(x)
  max(x)
  range(x)
  sum(x)
  summary(x)

 
# }
# NOT RUN {
    n <- .Machine$integer.max
    x <- !bit(n)
    N <- 1000000L  # batchsize
    B <- n %/% N   # number of batches
    R <- n %% N    # rest

    message("Batched sum (52.5 sec on Centrino duo)")
    system.time({
      s <- 0L
      for (b in 1:B){
        s <- s + sum(x[((b-1L)*N+1L):(b*N)])
      }
      if (R)
        s <- s + sum(x[(n-R+1L):n])
    })

    message("Batched sum saving repeated memory allocation for the return vector
    (44.4 sec on Centrino duo)")
    system.time({
      s <- 0L
      l <- logical(N)
      for (b in 1:B){
        .Call("R_bit_extract", x, length(x), ((b-1L)*N+1L):(b*N), l, PACKAGE = "bit")
        s <- s + sum(l)
      }
      if (R)
        s <- s + sum(x[(n-R+1L):n])
    })

    message("C-coded sum (3.1 sec on Centrino duo)")
    system.time(sum(x))
 
# }