# This program input the pima data and demonstrates
# how to 1) draw partial regression plots
#        2) regress on partial data
# Note that you should install mlbench package to use 
# the pima data set. 
# Created by C. Andy Tsao on 040503.

library(MASS); library(mlbench)
# Data Step
data("PimaIndiansDiabetes"); attach(PimaIndiansDiabetes)
pima<-PimaIndiansDiabetes; attach(pima)
x1<-mass; x2<-age; y<-glucose ;
yr2<-lm(y~x2); r12<-lm(x1~x2);
plot(yr2$res~r12$res)

dim(pima)
index<-1:768
m2<-450
geindex<-sample(index,m2)
spima<-data.frame(pima[geindex,])
sout<-lm(glucose~mass+age,data=spima)
summary(sout)

restout<-lm(y[x1>10]~x1[x1>10])
summary(restout)
summary(lm(y~x1))
plot(y~x1)
abline(lm(y~x1))
abline(restout)