R: Opening an ff file

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` | an `ff` or `ffdf` object
`readonly` | `readonly`
`pagesize` | number of bytes to use as pagesize or NULL to take the pagesize stored in the `physical` attribute of the ff object, see `getalignedpagesize`
`caching` | one of 'mmnoflush' or 'mmeachflush', see `ff`
`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()

[Package ff version 2.2-13 Index]