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Get ramclass and ramattribs

ramattribs.rd

Functions ramclass and ramattribs return the respective virtual attributes, that determine which class (and attributes) an ff object receives when subscripted (or coerced) to ram.

Usage

ramclass(x, ...)
# S3 method for class 'ff'
ramclass(x, ...)
# Default S3 method
ramclass(x, ...)
ramattribs(x, ...)
# S3 method for class 'ff'
ramattribs(x, ...)
# Default S3 method
ramattribs(x, ...)

Arguments

x

x

...

further arguments (not used)

Details

ramclass and ramattribs provide a general mechanism to store atomic classes in ff objects, for example factor – see levels.ff – and POSIXct, see the example.

Value

ramclass returns a character vector with classnames and ramattribs returns a list with names elemens just like attributes. The vectors ramclass_excludes and ramattribs_excludes name those attributes, which are not exported from ff to ram objects when using as.ram.

Author

Jens Oehlschlägel

See also

ff, virtual, as.ram, levels.ff, attributes, DateTimeClasses

Examples

  x <- ff(as.POSIXct(as.POSIXlt(Sys.time(), "GMT")), length=12)
  x
#> ff (open) double length=12 (12)
#>                        [1]                        [2] 
#> 2026-08-03 14:06:09.524621 2026-08-03 14:06:09.524621 
#>                        [3]                        [4] 
#> 2026-08-03 14:06:09.524621 2026-08-03 14:06:09.524621 
#>                        [5]                        [6] 
#> 2026-08-03 14:06:09.524621 2026-08-03 14:06:09.524621 
#>                                                   [7] 
#>                          : 2026-08-03 14:06:09.524621 
#>                        [8]                        [9] 
#> 2026-08-03 14:06:09.524621 2026-08-03 14:06:09.524621 
#>                       [10]                       [11] 
#> 2026-08-03 14:06:09.524621 2026-08-03 14:06:09.524621 
#>                       [12] 
#> 2026-08-03 14:06:09.524621 
  ramclass(x)
#> [1] "POSIXct" "POSIXt" 
  ramattribs(x)
#> $tzone
#> [1] "GMT"
#> 
  class(x[])
#> [1] "POSIXct" "POSIXt" 
  attributes(x[])
#> $tzone
#> [1] "GMT"
#> 
#> $class
#> [1] "POSIXct" "POSIXt" 
#> 
  virtual(x)$ramattribs$tzone = NULL
  attributes(x[])
#> $class
#> [1] "POSIXct" "POSIXt" 
#> 
  rm(x); gc()
#>           used (Mb) gc trigger  (Mb) max used  (Mb)
#> Ncells 1252708 67.0    2239654 119.7  2239654 119.7
#> Vcells 2307393 17.7    8388608  64.0  8387257  64.0