# ANDERSON'S IRIS DATASET:
iris
attach(iris)
SL=Sepal.Length
SW=Sepal.Width
PL=Petal.Length
PW=Petal.Width

# HISTOGRAM:
? hist()
hist(SL,breaks=15,col="blue")

# BOX PLOT:
? boxplot()
boxplot(PL)
boxplot(iris)
boxplot(SL~Species)

# STEM & LEAF PLOT:
? stem()
stem(SL)

# SCATTER PLOTS OF RESIDUALS
# DEFINING EXAMPLE X,Y
Y=SL
X=SW

# PLOT OF RESIDUALS:
e=resid(lm(Y~X))
plot(X,e,col="black")
abline(0,0,col="blue")

# RESIDUALS VS FITTED VALUES:
e=resid(lm(Y~X))
Yh=fitted(lm(Y~X))
plot(Yh,e,col="blue")
abline(0,0,col="brown")


# PLOT OF SEMI-STUDENTIZED RESIDUALS:
K=summary(lm(Y~X),digits=10)
sqrtMSE=K$sigma
sqrtMSE
print(summary(lm(Y~X)),digits=10)
ess=e/sqrtMSE
plot(X,ess,col="red")
abline(0,0,col="blue")

#STANDARD DIAGNOSTIC PLOTS FROM A LINEAR MODEL:
LM=lm(Y~X)
op = par(mfrow = c(2, 2), pty = "s")       
plot(LM)
par(op)

# LOWESS LINES:
# USING TOLUCA DATA
K=read.table("c:/2008LinearModelsData/toluca.txt")
attach(K)
X=V1
Y=V2
plot(lowess(Y~X),type="l",col="red")
points(X,Y,col="blue")