R: Virtual transpose

vt {ff} | R Documentation

## Virtual transpose

### Description

The `vt` generic does a matrix or array transpose by modifying `virtual` attributes rather than by physically copying matrix elements.

### Usage

    vt(x, ...)
    ## S3 method for class 'ff'
    vt(x, ...)
    ## Default S3 method:
    vt(x, ...)
    ## S3 method for class 'ff'
    t(x)

### Arguments

`x` | an ff or ram object
`...` | further arguments (not used)

### Details

The `vt.ff` method does transpose through reversing `dim.ff` and `dimorder`. The `vt.default` method is a wrapper to the standard transpose `t`.
The `t.ff` method creates a transposed `clone`.
If `x` has a virtual window `vw` defined, `vt.ff` returns an ff object with a transposed virtual window, the `t.ff` method return a transposed clone of the virtual window content only.

### Value

an object that behaves like a transposed matrix

### Author(s)

Jens Oehlschlägel

### See Also

`dim.ff`, `vw`, `virtual`

### Examples

      x <- ff(1:20, dim=c(4,5))
      x
      vt(x)
      y <- t(x)
      y
      vw(x) <- cbind(c(1,3,0),c(1,4,0))
      x
      vt(x)
      y <- t(x)
      y
      rm(x,y); gc()

[Package ff version 2.2-13 Index]