[R] ggplot & annotating charts

[Gabor Grothendieck]

Note that even without substantial changes the code could be
shortened by making use of read.zoo and other items illustrated
below:

library(zoo)

vix.url <- "http://www.cboe.com/publish/ScheduledTask/MktData/datahouse/vixcurrent.csv"
v <- read.zoo(vix.url, header = TRUE, sep = ",", format = "%m/%d/%Y",
	FUN = as.yearmon, aggregate = max)[, 4]

plot(v, type = "n", ylab = "S&P Volatility", xlab = "Date")

# might want to make next two lines into function
u <- par("usr")
rect(as.yearmon(2007-8"), u[3], as.yearmon("2009-11"), u[4],
   border = 0, col = "grey")

lines(v)
axis(1, floor(time(v)), labels = FALSE, tcl = -1)

There is also an example of background shadings in ?xyplot.zoo


On Tue, Nov 4, 2008 at 9:49 AM, simeon duckworth
<simeonduckworth at gmail.com> wrote:
> Dear "R-listers"
>
> I've been trying to figure out how to annotate charts in ggplot (ie add text
> to line charts, highlighted boxes etc).  By and large, I can get close to
> what i want with base graphics, but would ideally like to use ggplot
> whenever possible (additionally, i would like to add text labels
> automatically to the chart).  The code is below
>
> I suspect I need to use geom_rect, but what is foxing me is how to set up
> the aes() parameters.
>
> I'd be very grateful for any help
>
> thanks
>
> simeon
>
> ###################
> require(zoo)
> require(chron)
>
> vix <-read.csv("
> http://www.cboe.com/publish/ScheduledTask/MktData/datahouse/vixcurrent.csv",
>               header=T,sep=",", na.strings="")
> names(vix) <- tolower(names(vix))
> vix$dates <- chron(as.character(vix$date),out.format="d-mon-y")
> vix.z <- zoo(vix[,-1],vix$dates)
> vix.close1<-aggregate(vix.z[,4],as.yearmon,max)
>
> # 1990 - 2003
> vix.ar1 <- read.csv("C:/Data/MindShare/Recession/vixarchive.csv",
>           header=T,sep=",", quote="",na.strings="n/a")
> names(vix.ar1) <- tolower(names(vix.ar1))
> vix.ar1$dates <- chron(as.character(vix.ar1$date),out.format="d-mon-y")
> vix.ar1.z <- zoo(vix.ar1[,-1],vix.ar1$dates)
> vix.close2<-aggregate(vix.ar1.z[,4],as.yearmon,max)
> vix.close<-rbind(vix.close1,vix.close2)
>
> op <- par(mar = c(6, 8, 6, 6) + 0.1)
> gulf1 <- as.yearmon("1990-8-2")
> gulf2 <- as.yearmon("1991-2-28")
> asia1 <- as.yearmon("1997-9-11")
> asia2 <- as.yearmon("1998-11-14")
> sep1 <- as.yearmon("2001-9-11")
> sep2 <- as.yearmon("2002-9-14")
> crunch1 <- as.yearmon("2007-8-9")
> crunch2 <- as.yearmon("2009-11-14")
> plot(vix.close, type = "n",ylab="S&P500 volatility",
>     xlab="Date",cex.axis=1.5,cex.lab=1.7,ylim=c(0,90) )
> rect(gulf1, par("usr")[3], gulf2,
> par("usr")[4],col=rgb(195,188,175,maxColorValue=255),border=0)
> rect(asia1, par("usr")[3], asia2,
> par("usr")[4],col=rgb(195,188,175,maxColorValue=255),border=0)
> rect(sep1, par("usr")[3], sep2, par("usr")[4],
> col=rgb(195,188,175,maxColorValue=255),border=0)
> rect(crunch1, par("usr")[3], crunch2, par("usr")[4],
> col=rgb(195,188,175,maxColorValue=255), border = 0)
> lines(vix.close,lwd=3,col=rgb(45,12,75,maxColorValue=255))
> title(main="US STOCK MARKET VOLATILITY 1962-2008 ",adj=0,cex.main=2.3)
>
>        [[alternative HTML version deleted]]
>
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