dr (version 3.0.10)

coord.hyp.basis: Internal function to find the basis of a subspace

Description

If a dimension reduction object has $p$ dimension, returns a $p \times r$ matrix whose columns space a subspace specified by a formula.

Usage

coord.hyp.basis(object, spec, which = 1)

Arguments

object

A dr object

spec

A one-sided formula, see below

which

either +1 or $-1$; see below

Value

A matrix corresponding to the value of spec and which given.

Details

The workings of this function is best explained by an example. Suppose the dr object was created with the formula y~x1+x2+x3+x4, so we have $p=4$ predictors. A matrix that spans the subspace of $R^4$ specified by Span(x1,x2,x3,x4) is simply the identity matrix of order 4.

This function will return a subset of the columns of this identity matrix, as determined by spec. For example, if spec = ~.-(x3+x4), the function returns the columns corresponding to x1 and x2 if which=+1 or the columns corresponding to x3 and x4 if which=$-1$. Similarly, if spec=~x1+x2, the same matrices will be returned.

See Also

dr.coordinate.test

Examples

data(ais)
s1 <- dr(LBM~log(Ht)+log(Wt)+log(RCC)+log(WCC)+log(Hc)+log(Hg),
         data=ais,method="sir")
coord.hyp.basis(s1,~.-log(Wt)-log(Hg))