############# R code for Hwk 1, problems 3.56-57 ################
# create file prob3.56.txt containing the data with column names
mo m2   m3
1  2.25 2.81
2  2.27 2.84
3  2.28 2.86
4  2.29 2.88
5  2.31 2.9
6  2.32 2.92
7  2.35 2.96
8  2.37 2.99
9  2.40 3.02
10 2.42 3.04
11 2.43 3.05
12 2.42 3.05
13 2.44 3.08
14 2.47 3.1
15 2.49 3.1
16 2.51 3.13
17 2.53 3.17
18 2.53 3.18
19 2.54 3.19
20 2.55 3.2

# reads in data and uses col names instead of default V1, V2, V3
ms<-read.table("prob3.56.txt", header=T)

# make data columns accessible by name
attach(ms)

# can now access each data vector by its name. Here's m2
m2

# divide plotting device into 4 regions, and do a scatter plot m2 vs. m3
par(mfcol=c(2,2))
plot(m2,m3,xlab="M2",ylab="M3")
title("Scatter plot of M2 vs. M3")

# time series plot shows trends better. First just set the axes, and labels
plot(mo,m3,type="n",ylim=c(2.25,3.20),xlab="Month",ylab="Money Supply (trillions of dollars)")
# now add m2 with line type 1, m3 with line type 2, and connect pts
# with lines
lines(m2,lty=1)
lines(m3,lty=2)
# finally, add a legend and title
legend(1,3.2,legend=c("M2","M3"),lty=1:2)
title("Time series plot of M2 and M3")