Cloning ff and ram objects

clone physically duplicates ff (and ram) objects and can additionally change some features, e.g. length.

Usage

# S3 method for class 'ff'
clone(x
, initdata = x
, length = NULL
, levels = NULL
, ordered = NULL
, dim = NULL
, dimorder = NULL
, bydim = NULL
, symmetric = NULL
, fixdiag = NULL
, names = NULL
, dimnames = NULL
, ramclass = NULL
, ramattribs = NULL
, vmode = NULL
, update  = NULL
, pattern = NULL
, filename = NULL
, overwrite = FALSE
, pagesize = NULL
, caching = NULL
, finalizer = NULL
, finonexit = NULL
, FF_RETURN = NULL
, BATCHSIZE = .Machine$integer.max
, BATCHBYTES = getOption("ffbatchbytes")
, VERBOSE = FALSE
, ...)

Arguments

x: x
initdata: scalar or vector of the .vimplemented vmodes, recycled if needed, default 0, see also as.vmode and vector.vmode
length: optional vector length of the object (default: derive from 'initdata' or 'dim'), see length.ff
levels: optional character vector of levels if (in this case initdata must be composed of these) (default: derive from initdata)
ordered: indicate whether the levels are ordered (TRUE) or non-ordered factor (FALSE, default)
dim: optional array dim, see dim.ff and array
dimorder: physical layout (default seq_along(dim)), see dimorder and aperm
bydim: dimorder by which to interpret the 'initdata', generalization of the 'byrow' paramter in matrix
symmetric: extended feature: TRUE creates symmetric matrix (default FALSE)
fixdiag: extended feature: non-NULL scalar requires fixed diagonal for symmetric matrix (default NULL is free diagonal)
names: see names
dimnames: NOT taken from initdata, see dimnames
ramclass: class attribute attached when moving all or parts of this ff into ram, see ramclass
ramattribs: additional attributes attached when moving all or parts of this ff into ram, see ramattribs
vmode: virtual storage mode (default: derive from 'initdata'), see vmode and as.vmode
update: set to FALSE to avoid updating with 'initdata' (default TRUE) (used by ffdf)
pattern: root pattern for automatic ff filename creation (default "ff"), see also physical
filename: ff filename (default tmpfile with 'pattern' prefix), see also physical
overwrite: set to TRUE to allow overwriting existing files (default FALSE)
pagesize: pagesize in bytes for the memory mapping (default from getOptions("ffpagesize") initialized by getdefaultpagesize), see also physical
caching: caching scheme for the backend, currently 'mmnoflush' or 'mmeachflush' (flush mmpages at each swap, default from getOptions("ffcaching") initialized with 'memorymap'), see also physical
finalizer: name of finalizer function called when ff object is removed, (default "deleteIfOpen" from getOptions("fffinalizer"))), standard finalizers are close.ff, delete.ff and deleteIfOpen.ff, see also reg.finalizer
finonexit: logical scalar determining whether finalizer is also called when R is closed via q, (default TRUE from getOptions("fffinonexit"))
FF_RETURN: logical scalar or ff object to be used. The default NULL creates a ff or ram clone, TRUE returns a ff clone, FALSE returns a ram clone. Handing over an ff object here uses this or stops if not ffsuitable
BATCHSIZE: integer scalar limiting the number of elements to be processed in update.ff when length(initdata)>1, default from getOption("ffbatchsize")
BATCHBYTES: integer scalar limiting the number of bytes to be processed in update.ff when length(initdata)>1, default from getOption("ffbatchbytes"), see also .rambytes
VERBOSE: set to TRUE for verbosing in update.ff when length(initdata)>1, default FALSE
...: further arguments to the generic

Details

clone is generic. clone.ff is the workhorse behind as.ram and as.ff. For creating the desired object it calls ff which calls update for initialization.

Value

an ff or ram object

Author

Jens Oehlschlägel

Examples

  x <- ff(letters, levels=letters)
  y <- clone(x, length=52)
  rm(x,y); gc()
#>           used (Mb) gc trigger  (Mb) max used  (Mb)
#> Ncells 1224777 65.5    2239654 119.7  2239654 119.7
#> Vcells 2243719 17.2    8388608  64.0  5871749  44.8