scale {base} | R Documentation |

## Scaling and Centering of Matrix-like Objects

### Description

`scale`

is generic function whose default method centers and/or
scales the columns of a numeric matrix.

### Usage

scale(x, center = TRUE, scale = TRUE)

### Arguments

`x` |
a numeric matrix(like object). |

`center` |
either a logical value or a numeric vector of length
equal to the number of columns of `x` . |

`scale` |
either a logical value or a numeric vector of length
equal to the number of columns of `x` . |

### Details

The value of `center`

determines how column centering is
performed.
If `center`

is a numeric vector with length equal to the number
of columns of `x`

, then each column of `x`

has the
corresponding value from `center`

subtracted from it.
If `center`

is `TRUE`

then centering is done by subtracting
the column means (omitting `NA`

s) of `x`

from their
corresponding columns, and if `center`

is `FALSE`

,
no centering is done.

The value of `scale`

determines how column scaling is performed
(after centering).
If `scale`

is a numeric vector with length equal to the number of
columns of `x`

, then each column of `x`

is divided by the
corresponding value from `scale`

.
If `scale`

is `TRUE`

then scaling is done by dividing the
(centered) columns of `x`

by their root-mean-square, and if
`scale`

is `FALSE`

, no scaling is done.

The root-mean-square for a column is obtained by computing the
square-root of the sum-of-squares of the non-missing values in the
column divided by the number of non-missing values minus one.

### Value

For `scale.default`

, the centered, scaled matrix. The numeric
centering and scalings used (if any) are returned as attributes
`"scaled:center"`

and `"scaled:scale"`

### References

Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988)
*The New S Language*.
Wadsworth & Brooks/Cole.

### See Also

`sweep`

which allows centering (and scaling) with
arbitrary statistics.

For working with the scale of a plot, see `par`

.

### Examples

require(stats)
x <- matrix(1:10, nc=2)
(centered.x <- scale(x, scale=FALSE))
cov(centered.scaled.x <- scale(x))# all 1

[Package

*base* version 2.2.1

Index]