library(regtools)
library(freqparcoord)
data(mlb)
mlb1 <- mlb[,c(4,6,5)]
xd <- preprocessx(mlb1[,1:2],35)
neighborvars <- knnest(mlb1$Weight,xd,35)$regest
wts <- 1 / neighborvars
summary(lm(mlb$Weight ~ mlb$Height+mlb$Age, weights=wts))
summary(lm(mlb$Weight ~ mlb$Height+mlb$Age))

library(freqparcoord)
data(mlb)
mlb <- mlb[,c(4,6,5)]
m70 <- mlb[mlb$Height >= 70 & mlb$Height <= 77,]
vars <- tapply(m70$Weight,m70$Height,var)
wts <- 1 / vars[m70$Height-69]
summary(lm(m70$Weight ~ m70$Height, weights=wts))
summary(lm(m70$Weight ~ m70$Height))