open.ff {ff} | R Documentation |
Opening an ff file
Description
open.ff
opens an ff file, optionally marking it readonly and optionally specifying a caching scheme.
Usage
## S3 method for class 'ff'
open(con, readonly = FALSE, pagesize = NULL, caching = NULL, assert = FALSE, ...)
## S3 method for class 'ffdf'
open(con, readonly = FALSE, pagesize = NULL, caching = NULL, assert = FALSE, ...)
Arguments
con |
|
readonly |
|
pagesize |
number of bytes to use as pagesize or NULL to take the pagesize stored in the |
caching |
one of 'mmnoflush' or 'mmeachflush', see |
assert |
setting this to TRUE will give a message if the ff was not open already |
... |
further arguments (not used) |
Details
ff objects will be opened automatically when accessing their content and the file is still closed.
Opening ffdf objects will open all of their physical
components including their row.names
if they are is.ff
Value
TRUE if object could be opened, FALSE if it was opened already (or NA if not all components of an ffdf returned FALSE or TRUE on opening)
Author(s)
Jens Oehlschlägel
See Also
ff
, close.ff
, delete
, deleteIfOpen
, getalignedpagesize
Examples
x <- ff(1:12)
close(x)
is.open(x)
open(x)
is.open(x)
close(x)
is.open(x)
x[]
is.open(x)
y <- x
close(y)
is.open(x)
rm(x,y); gc()