plot4.R

# Plot 4
# open device
if(!file.exists("Graphics")) dir.create("Graphics")
png(filename = "./Graphics/plot4.png", width = 480, height = 480, units="px")

# plot figure
Sys.setlocale(category = "LC_ALL", locale = "english")
par(mfrow = c(2, 2))
plot(data$DateTime, data$Global_active_power, xlab = "",
                                              ylab = "Global Active Power (kilowatt)",
                                              type = "l")
plot(data$DateTime, data$Voltage, xlab = "datetime", 
                                  ylab = "Voltage", 
                                  type = "l")
plot(data$DateTime, data$Sub_metering_1,  xlab = "", 
                                          ylab = "Energy sub metering", 
                                          type = "l")
lines(data$DateTime, data$Sub_metering_2, col = "red")
lines(data$DateTime, data$Sub_metering_3, col = "blue")
legend("topright",  col = c("black", "red", "blue"), 
                    legend = c("Sub_metering_1", "Sub_metering_2", "Sub_metering_3"),
                    lwd = 1)
plot(data$DateTime, data$Global_reactive_power, xlab = "datetime", 
                                                ylab = "Global_reactive_power", 
                                                type = "l")
# close device
dev.off()