plot3.R

library(dplyr)
dat <- read.csv('household_power_consumption.txt', sep=';',
                na.strings = '?')

fil_dat <- filter(dat, dat$Date == '1/2/2007' | dat$Date == '2/2/2007')
fil_dat$datetime <- strptime(paste(fil_dat$Date, fil_dat$Time), '%d/%m/%Y %T')

png(filename='plot3.png', width=480, height=480)
with(fil_dat, plot(datetime, Sub_metering_1, type='n', 
                   ylab='Energy sub metering',
                   xlab=''))
with(fil_dat, lines(datetime, Sub_metering_1))
with(fil_dat, lines(datetime, Sub_metering_2, col='red'))
with(fil_dat, lines(datetime, Sub_metering_3, col='blue'))
legend('topright', lty=1, col=c('black', 'red', 'blue'),
       legend=c('Sub_metering_1', 'Sub_metering_2', 'Sub_metering_3'))
dev.off()