plot3.R

# plot3.R - Time Series of Global Active Power by submeter
# Set working directory
# dir <- "~/workspace/r_workspace/coursera/Expolaratory/ExData_Plotting1/"
# setwd(dir)
# Set col classes for faster loading
col_classes <- c('character', 'character', rep('numeric', 7))
# Read data, convert dates and subset on two days in February 2007
data <- read.table('household_power_consumption.txt', sep=';', header=T,
                    colClasses = col_classes,
                    na.strings='?'
                  )
# Concate Date and Time and convert into date time and bind to `date$DateTime`
data$DateTime <- strptime(paste(data$Date, data$Time),
                          "%d/%m/%Y %H:%M:%S")
data <- subset(data,
                as.Date(DateTime) >= as.Date("2007-02-01") &
                as.Date(DateTime) <= as.Date("2007-02-02")
              )

# Open plot3.png
png("plot3.png", height=480, width=480)

# Builds plot and draws first sub_metering_1 plot
plot(data$DateTime,
      data$Sub_metering_1,
      pch=NA,
      xlab="",
      type="l",
      ylab="Energy sub metering"
    )
lines(data$DateTime, data$Sub_metering_2, col='red')
lines(data$DateTime, data$Sub_metering_3, col='blue')
# Draw the legends
legend('topright',
        c("Sub_metering_1", "Sub_metering_2", "Sub_metering_3"),
        lty = c(1,1,1),
        col = c('black', 'red', 'blue')
      )

# Close PNG file
dev.off()