Plot Apple's share price with googleVis and gvisAnnotatedTimeLine

gistfile1.r

## Markus Gesmann, February 2012
## This R script requires the googleVis package, 
## a browser with Flash and an Internet connection.

gvisWeeklyStockData <- function(tckr = "AAPL", 
		                chartid ="Apple", 
				start.year=1984){

require(googleVis)
d <- Sys.time() 
current.year <- format(d, "%Y")
current.month <- format(d, "%m")
current.day <- format(d, "%d")
## Yahoo finance sets January to 00 hence: 
current.month <- as.numeric(current.month)  - 1
current.month <- ifelse(current.month < 10, 
                        paste("0", current.month, sep=""), m)
## Get weekly stock prices for Apple Inc.

## Get data from Yahoo! Finance
fn <- sprintf('http://ichart.finance.yahoo.com/table.csv?s=%s&a=08&b=7&c=%s&d=%s&e=%s&f=%s&g=w&ignore=.csv',
              tckr, start.year, current.month, current.day, current.year)
data <- read.csv(fn, colClasses=c("Date", rep("numeric",6)))

## Reshape the data into a long format, see also
## http://lamages.blogspot.com/2012/02/reshape-function.html
stock <- reshape(
                data[,c("Date","Close","Volume")], 
                idvar="Date", 
                times=c("Close", "Volume"), 
                timevar="Type", 
                varying=list(c("Close", "Volume")),
                v.names="Value", direction="long" 
                )

## Calculate previous two years for zoom start time
lyd <- as.POSIXlt(as.Date(d))
lyd$year <- lyd$year-2
lyd <- as.Date(lyd)

## Create annotated time line chart 
gvisAnnotatedTimeLine(
                     stock, datevar="Date", 
                     numvar="Value", 
                     idvar="Type", 
                     options=list( 
                       colors="['blue', 'lightblue']", 
                       zoomStartTime=lyd, 
                       zoomEndTime=as.Date(d), 
                       legendPosition='newRow', 
                       width=600, height=400, 
                       scaleColumns='[0,1]', 
                       scaleType='allmaximized'), 
                       chartid=chartid
                       )
}                       

output <- gvisWeeklyStockData(tckr = "AAPL", 
			     chartid ="Apple", 
			     start.year=1984)
plot(output)