# K. Ensor (ensor@rice.edu)
# Rice Univeristy
#
# Three functions are created.
# kacf - returns the ACF and plots it correctly
# kpacf - returns the PACF and plots it correctly
# kdescrip - produces 
#			- time series plot
#			- histogram
#			- correlogram
#			- partial correlogram
#			- lagged scatterplots up to lag 10
#		INPUT is x (the series) and xtitle (the title of the series)
#

kacf<-function(x)
{
xacf<-acf(x,plot=F,type="correlation")
nlag<-length(xacf$lag)
print(nlag)
nzero<-rep(0,nlag)
plot(c(-1,0,xacf$lag,nlag+1),c(0,0,nzero,0),type="l",ylim=c(-1,1),xlim=c(0,nlag-1),xlab="Lag",ylab="ACF")
segments(xacf$lag,nzero,xacf$lag,nzero+xacf$acf)
title("ACF")
return(xacf)
}

kpacf<-function(x)
{
xpacf<-acf(x,plot=F,type="partial")
nlag<-length(xpacf$lag)
nzero<-rep(0,nlag)
plot(c(-1,0,xpacf$lag,nlag+1),c(0,0,nzero,0),type="l",ylim=c(-1,1),xlim=c(0,nlag-1),xlab="Lag",ylab="ACF")
segments(xpacf$lag,nzero,xpacf$lag,nzero+xpacf$acf)
title("PACF")
return(xpacf)
}

#DESCRIPTIVE PLOTS

kdescrip<-function(x,xtitle)
{
split.screen(c(2,1)) #split screen into two parts
split.screen(c(1,3),screen=2) #split the bottom graph into three parts

screen(1)
ts.plot(x)
title(main=xtitle)

screen(3)
hist(x,main="Histogram",xlab=xtitle)

screen(4)
xacf<-kacf(x)
#kacf(x)

screen(5)
kpacf(x)

close.screen(all=T)

lag.plot(x,layout=c(2,5),lags=10)
}