Scaling and Centering of Matrix

Description

scale centers and/or scales the columns of a FlashR matrix.

Usage

## S4 method for signature 'fm'
scale(x, center = TRUE, scale = TRUE)

Arguments

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 NAs) 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 standard deviations if center is TRUE, and the root mean square otherwise. If scale is FALSE, no scaling is done.

The root-mean-square for a (possibly centered) column is defined as sqrt(sum(x^2)/(n-1)), where x is a vector of the non-missing values and n is the number of non-missing values. In the case center = TRUE, this is the same as the standard deviation, but in general it is not.

Value

a FlashR matrix.

Author(s)

Da Zheng <dzheng5@jhu.edu>

Examples

mat <- fm.runif.matrix(100, 10)
mat <- scale(mat)