R/qplotreg.R

In musto101/wilcox_R: What the package does (short line)

qplotreg <-
function(x, y,qval=c(.2,.8),q=NULL,plotit=TRUE,xlab="X",ylab="Y",xout=FALSE,outfun=out,...){
#
# Compute the quantile regression line for each of the
# quantiles indicated by qval.
# plotit=TRUE, plot the results.
#	
if(!is.null(q))qval=q
xy=elimna(cbind(x,y))
if(ncol(xy)>2)stop("Only One Predictor Allowed")
x=xy[,1]
y=xy[,2]
if(xout){
x<-as.matrix(x)
flag<-outfun(x,...)$keep
x<-x[flag,]
y<-y[flag]
}
n<-length(qval)
coef<-matrix(NA,ncol=2,nrow=n)
x<-as.matrix(x)
if(ncol(x)>1)stop("This version allows one predictor only.")
if(plotit)plot(x,y,xlab=xlab,ylab=ylab)
for(it in 1:n){
coef[it,]<-qreg(x,y,qval=qval[it],pr=FALSE)$coef
dimnames(coef)=list(NULL,c("Inter.","Slope"))
if(plotit)abline(coef[it,1],coef[it,2])
}
coef
}