% fields, Tools for spatial data
% Copyright 2004-2011, Institute for Mathematics Applied Geosciences
% University Corporation for Atmospheric Research
% Licensed under the GPL -- www.gpl.org/licenses/gpl.html

\name{transformx}
\alias{transformx}
\title{
  Linear transformation   
}
\description{
Linear transformation of each column of a matrix. There are several 
choices of the type of centering and scaling.  
}
\usage{
transformx (x, scale.type = "unit.sd", x.center, x.scale)
}
\arguments{
\item{x}{
Matrix with columns to be transformed.
}
\item{scale.type}{
Type of transformation the default is "unit.sd": subtract the mean and 
divide by the standard deviation. 
Other  choices are "unscaled" (do nothing),  "range" (transform to 
[0,1]),"user" (subtract a supplied location and divide by a scale).
}
\item{x.center}{
A vector of centering values to subtract from each column. 
}
\item{x.scale}{
A vector of scaling values to subtract from each column.
}
}
\value{
A matrix whose columns have between transformed.
This matrix also has the attributes: scale.type, x.center and y.center 
with the transformation information. 
}
\details{
After deciding what the centering and scaling values should be for each 
column of x, this function just calls the standard utility scale. 
This function was created partly to attach the transformation information 
as attributes to the transformed matrix. It is used in Krig, cover.design, 
krig.image etc. to transform the independent variables.   
}
\seealso{
scale
}
\examples{
#
newx<-transformx( ozone$x, scale.type="range")
}
\keyword{manip}
% docclass is function
% Converted by Sd2Rd version 1.21.