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

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