R/signs.shape.R

In SpatialNP: Multivariate Nonparametric Methods Based on Spatial Signs and Ranks

`signs.shape` <- function(X, fixed.loc=FALSE, location=NULL, init=NULL,  steps=Inf, eps=1e-6, maxiter=100, na.action=na.fail)
{
 X <- na.action(X)
 X<-as.matrix(X)  

 p<-dim(X)[2]
 if(p==1) return(diag(1))

 if (is.null(init)) {V<-covshape(X)
 }else{ if(is.function(init)) init<-init(X)
  V<-to.shape(init)
 }
 if (is.null(location)) {mu<-colMeans(X)
 }else{ if(is.function(location)) location<-location(X)
  mu<-location
 }
 if(is.finite(steps)) maxiter<-Inf
 
 if(!fixed.loc){
 
 differ <- Inf
 iter <- 0
 while(TRUE)
 {
   if(iter>=steps) return(res)
   if(iter>=maxiter) warning("maxiter reached")
   iter<-iter+1

   sqrtV<-mat.sqrt(V)  
   A<-solve(sqrtV)
   Z<-sweep(X,2,mu)%*%t(A)  
   mu.new<-mu+sqrtV%*%center.step(Z,rep(0,p)) 
   V.new<-sqrtV%*%SCov(Z,rep(0,p))%*%sqrtV   
   V.new<-to.shape(V.new)
   res<-V.new
   attr(res,"location")<-mu.new 
   if(all(is.infinite(steps),mat.norm(V.new-V)<eps,sqrt(sum((mu.new -mu)^2))<eps)) 
    return(res)
   mu<-mu.new
   V<-V.new
  }

 }else
 { 
 iter<-0
 while(TRUE)
 {
   if(iter>=steps) return(res)
   if(iter>=maxiter) warning("maxiter reached")
   iter<-iter+1
   sqrtV<-mat.sqrt(V)  
   A<-solve(sqrtV)
   Z<-sweep(X,2,mu)%*%t(A)  
   V.new<-sqrtV%*%SCov(Z,rep(0,p))%*%sqrtV   
   V.new<-to.shape(V.new)
   res<-V.new
   attr(res,"location")<-mu
   if(all(is.infinite(steps), mat.norm(V.new-V)<eps)) {return(res)}
   V<-V.new
 }
 }
}