R/kslope.R

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

kslope <-
function(x,y,pyhat=FALSE,pts=x){
#
# Estimate slope at points in pts using kernel method
#
# See Doksum et al. 1994, JASA, 89, 571-
#
m<-elimna(cbind(x,y))
x<-m[,1]
y<-m[,2]
n<-length(y)
sig<-sqrt(var(x))
temp<-idealf(x)
iqr<-(temp$qu-temp$ql)/1.34
A<-min(c(sig,iqr))
yhat<-NA
vval<-NA
vals<-NA
rhosq<-NA
for(k in 1:n){
temp1<-NA
for(j in 1:n){
temp1[j]<-((x[j]-x[k])/A)^2
}
epan<-ifelse(temp1<1,.75*(1-temp1),0) # Epanechnikov kernel, p. 76
chkit<-sum(epan!=0)
if(chkit >= 2){
temp4<-lsfit(x,y,wt=epan)
vals[k]<-temp4$coef[2]
}}
vals
}