plot4.R

source("loadData.R")

plot4 <- function() {
  
  data <- loadData()
  png("plot4.png", width=480, height=480)
  par(mfrow=c(2,2))
  
  #Plot 1
  plot(
    data$Time, 
    data$Global_active_power,
    type="l",
    xlab="",
    ylab="Global Active Power")
  
  # Plot 2
  plot(data$Time, data$Voltage, type="l", xlab="datetime", ylab="Voltage")
  
  # Plot 3
  plot(data$Time, data$Sub_metering_1, type="l", col="black", xlab="", ylab="Energy sub metering")
  lines(data$Time, data$Sub_metering_2, col="red")
  lines(data$Time, data$Sub_metering_3, col="blue")
  legend(
    "topright",
    col=c("black", "red", "blue"),
    c("Sub_metering_1", "Sub_metering_2", "Sub_metering_3"),    
    lwd=1,
    bty="n"   
  )
  
  #Plot 4
  plot(
    data$Time, 
    data$Global_reactive_power, 
    type="l",
    xlab="datetime", 
    ylab="Global_reactive_power"   
  )
  
  dev.off()
}