plot3.R

## plot3()
##
## Purpose: Look at time-series data, plotting various sub meters for two days in February
##
## Note: Assumes the dataset has already been unzipped and is sitting in the current working directory

plot3 <- function() {
  ## Read in the data
  data <- read.table("household_power_consumption.txt", header = T, sep = ";", colClasses = c(NA, NA, "numeric", "numeric", "numeric", "numeric", "numeric", "numeric", "numeric"), stringsAsFactors = F, na.strings = "?")
  
  ## Convert dates/times from character
  data$Date <- as.Date(data$Date, format = "%d/%m/%Y")
  data$Time <- strptime(data$Time, format = "%H:%M:%S")
  
  ## Restrict the dates to the first two days in February 2007
  data <- data[(data$Date > "2007-01-31" & data$Date < "2007-02-03"), ]
  
  
  
  ## Plot the sub metering data as a time series; generate PNG
  png(filename = "plot3.png")
  plot(data$DateTime, data$Sub_metering_1, main = "", type = "n", xlab = "", ylab = "Energy sub metering")
  lines(data$DateTime, data$Sub_metering_1)
  lines(data$DateTime, data$Sub_metering_2, col = "red")
  lines(data$DateTime, data$Sub_metering_3, col = "blue")
  legend("topright", pch = 1, col = c("black", "blue", "red"), legend = c("Sub_metering_1", "Sub_metering_2", "Sub_metering_3"))
  dev.off()
}