# testport.r		    illustrate portfolio functions in portfolio.r
# updates: 
# August 11, 2011
#   updated to work with R 2.13.1
options(digits=4, width=70)
source("http://faculty.washington.edu/ezivot/econ424/portfolio.r")
# Functions:
#	1. efficient.portfolio			compute minimum variance portfolio
#							                subject to target return
#	2. globalMin.portfolio			compute global minimum variance portfolio
#	3. tangency.portfolio			  compute tangency portfolio
#	4. efficient.frontier			  compute Markowitz bullet
#	5. getPortfolio					    create portfolio object
#

#
# Examples from Introduction to Financial Econometrics
#
asset.names = c("MSFT", "NORD", "SBUX")
er = c(0.0427, 0.0015, 0.0285)
names(er) = asset.names
covmat = matrix(c(0.0100, 0.0018, 0.0011,
		              0.0018, 0.0109, 0.0026,
		              0.0011, 0.0026, 0.0199),
		             nrow=3, ncol=3)
r.free = 0.005
dimnames(covmat) = list(asset.names, asset.names)
er
covmat
r.free

#
# compute equally weighted portfolio
ew = rep(1,3)/3
equalWeight.portfolio = getPortfolio(er=er,cov.mat=covmat,weights=ew)
class(equalWeight.portfolio)
names(equalWeight.portfolio)
equalWeight.portfolio
summary(equalWeight.portfolio)
plot(equalWeight.portfolio, col="blue")

#
# compute global minimum variance portfolio
gmin.port = globalMin.portfolio(er, covmat)
attributes(gmin.port)
print(gmin.port)
summary(gmin.port, risk.free=r.free)
plot(gmin.port, col="blue")

#
# compute efficient portfolio subject to target return
target.return = er["MSFT"]
e.port.msft = efficient.portfolio(er, covmat, target.return)
e.port.msft
summary(e.port.msft, risk.free=r.free)
plot(e.port.msft, col="blue")

#
# compute tangency portfolio
tan.port <- tangency.portfolio(er, covmat, r.free)
tan.port
summary(tan.port, risk.free=r.free)
plot(tan.port, col="blue")

#
# compute portfolio frontier
ef <- efficient.frontier(er, covmat, alpha.min=-2, 
                         alpha.max=1.5, nport=20)
attributes(ef)
ef

plot(ef)
plot(ef, plot.assets=TRUE, col="blue", pch=16)
points(gmin.port$sd, gmin.port$er, col="green", pch=16, cex=2)
points(tan.port$sd, tan.port$er, col="red", pch=16, cex=2)
text(gmin.port$sd, gmin.port$er, labels="GLOBAL MIN", pos=2)
text(tan.port$sd, tan.port$er, labels="TANGENCY", pos=2)    
sr.tan = (tan.port$er - r.free)/tan.port$sd
abline(a=r.free, b=sr.tan, col="green", lwd=2)


# plot portfolio frontier with tangency portfolio
sd.vals = sqrt(diag(covmat))
mu.vals = er
plot(ef$sd, ef$er, ylim=c(0, max(ef$er)), xlim=c(0, max(ef$sd)),
     xlab="portfolio sd", ylab="portfolio er", main="Efficient Portfolios")
text(sd.vals, mu.vals, labels=names(mu.vals))
abline(a=r.free, b=sr.tan)