Conversion between bit and ff boolean

Function as.ff.bit converts a bit vector to a boolean ff vector. Function as.bit.ff converts a boolean ff vector to a ff vector.

# S3 method for class 'bit'
as.ff(x, filename = NULL, overwrite = FALSE, ...)
# S3 method for class 'ff'
as.bit(x, ...)

Arguments

x

the source of conversion

filename

optionally a desired filename

overwrite

logical indicating whether we allow overwriting the target file

...

further arguments passed to ff in case as.ff.bit, ignored in case of as.bit.ff

Details

The data are copied bot bit-wise but integerwise, therefore these conversions are very fast. as.bit.ff will attach the ff filename to the bit vector, and as.ff.bit will - if attached - use THIS filename and SILENTLY overwrite this file.

Note

NAs are mapped to TRUE in 'bit' and to FALSE in 'ff' booleans. Might be aligned in a future release. Don't use bit if you have NAs - or map NAs explicitely.

Value

A vector of the converted type

Author

Jens Oehlschlägel

See also

bit, ff, as.ff, as.hi.bit

Examples

  l <- as.boolean(sample(c(FALSE,TRUE), 1000, TRUE))

  b <- as.bit(l)
  stopifnot(identical(l,b[]))
  b
#> bit length=1000 occupying only 32 int32
#>     1     2     3     4     5     6     7     8         993   994   995   996 
#> FALSE FALSE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE    .. FALSE FALSE  TRUE FALSE 
#>   997   998   999  1000 
#> FALSE  TRUE  TRUE  TRUE 
  f <- as.ff(b)
  stopifnot(identical(l,f[]))
  f
#> ff (open) boolean length=1000 (1024)
#>    [1]    [2]    [3]    [4]    [5]    [6]    [7]    [8]         [993]  [994] 
#>  FALSE  FALSE  FALSE   TRUE   TRUE   TRUE   TRUE   TRUE      :  FALSE  FALSE 
#>  [995]  [996]  [997]  [998]  [999] [1000] 
#>   TRUE  FALSE  FALSE   TRUE   TRUE   TRUE 
  b2 <- as.bit(f)
  stopifnot(identical(l,b2[]))
  b2
#> bit length=1000 occupying only 32 int32
#>     1     2     3     4     5     6     7     8         993   994   995   996 
#> FALSE FALSE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE    .. FALSE FALSE  TRUE FALSE 
#>   997   998   999  1000 
#> FALSE  TRUE  TRUE  TRUE 
  f2 <- as.ff(b2)
  stopifnot(identical(filename(f),filename(f2)))
  stopifnot(identical(l,f2[]))
  f
#> ff (open) boolean length=1000 (1024)
#>    [1]    [2]    [3]    [4]    [5]    [6]    [7]    [8]         [993]  [994] 
#>  FALSE  FALSE  FALSE   TRUE   TRUE   TRUE   TRUE   TRUE      :  FALSE  FALSE 
#>  [995]  [996]  [997]  [998]  [999] [1000] 
#>   TRUE  FALSE  FALSE   TRUE   TRUE   TRUE 
  rm(f,f2); gc()
#>           used (Mb) gc trigger  (Mb) max used  (Mb)
#> Ncells 1020252 54.5    1994352 106.6  1994352 106.6
#> Vcells 1880016 14.4    8388608  64.0  3877600  29.6