R: Getting and setting physical and virtual attributes of ff...

physical.ff {ff} | R Documentation

## Getting and setting physical and virtual attributes of ff objects

### Description

Functions for getting and setting physical and virtual attributes of ff objects.

### Usage

    ## S3 method for class 'ff'
    physical(x)
    ## S3 method for class 'ff'
    virtual(x)
    ## S3 replacement method for class 'ff'
    physical(x) <- value
    ## S3 replacement method for class 'ff'
    virtual(x) <- value

### Arguments

`x` | an ff object
`value` | a list with named elements

### Details

ff objects have physical and virtual attributes, which have different copying semantics: physical attributes are shared between copies of ff objects while virtual attributes might differ between copies. `as.ram` will retain some physical and virtual atrributes in the ram clone, such that `as.ff` can restore an ff object with the same attributes.

### Value

`physical` and `virtual` returns a list with named elements

### Author(s)

Jens Oehlschlägel

### See Also

`physical`, `physical.ffdf`, `ff`, `as.ram`;
`is.sorted` and `na.count` for applications of physical attributes;
`levels.ff` and `ramattribs` for applications of virtual attributes

### Examples

      x <- ff(1:12)
      x
      physical(x)
      virtual(x)
      y <- as.ram(x)
      physical(y)
      virtual(y)
      rm(x,y); gc()

[Package ff version 2.2-13 Index]