plot2.R

## Getting full dataset
## This conditional check is for test purposes only.
## If d exists in global environment, use it to avoid reading the file again
## For this to work, d must be defined in the Global Env
if ( !exists( "filedata" ) ) {
        filedata <- read.csv("Data/household_power_consumption.txt", header=T, sep=';', na.strings="?", 
                      check.names=F, stringsAsFactors=F, comment.char="", quote='\"')
}

## Subsetting the data
data <- subset( filedata, Date == "1/2/2007" | Date == "2/2/2007" )

## Convert Date to actual date
data$Date <- as.Date(data$Date, format="%d/%m/%Y")

## Add new column with datetime
datetime <- paste(data$Date, data$Time)
data$DateTime <- as.POSIXct(datetime)

## Plot 2
plot(data$Global_active_power~data$DateTime, ylab="Global Active Power (kilowatts)", 
     xlab="", type="l")


## Saving to file
dev.copy(png, file="plot2.png", height=480, width=480)
dev.off()