ExData_Plotting1/plot4.R at master · Simon99/ExData_Plotting1 · GitHub

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plot4 <- function(){
        library(stringr) ## for str_c()

        ##Read outcome data
        row_start = 66638
        row_end = 69517
        options(stringsAsFactors = FALSE)
        filename <- "household_power_consumption.txt"
        col_names = c("Date", "Time", "Global_active_power",
                      "Global_reactive_power", "Voltage", "Global_intensity",
                      "Sub_metering_1", "Sub_metering_2", "Sub_metering_3")
        data <-read.table(filename,
                          header = FALSE,
                          sep = ";",
                          na.strings = "?",
                          skip = row_start - 1,
                          nrows = row_end - row_start + 1,
                          colClasses = c(rep("character",2),rep("numeric",7)),
                          col.names = col_names
                          )
        # combine column 1 & 2 to generate correct time tag
        t_string <- str_c(data$Date, " ", data$Time)
        time_stamp <- strptime(t_string, format="%d/%m/%Y %H:%M:%S")

        #Plot and Record
        png(filename = "plot4.png",
            width = 480, height = 480, units = "px",
            bg = "white")

        par(mfcol = c(2, 2), mar = c(4, 4, 2, 1), oma = c(0, 0, 2, 0))
        plot(time_stamp, data$Global_active_power, type = "l", col = "black",
             xlab = "", ylab = "Global Active Power (Kilowatts)", main = "")
        plot(time_stamp, data$Sub_metering_1, type = "l", col = "black",
             xlab = "", ylab = "Global Active Power (Kilowatts)", main = "")
        points(time_stamp, data$Sub_metering_2, type = "l", col = "red")
        points(time_stamp, data$Sub_metering_3, type = "l", col = "blue")
        legend("topright", pch = "", col = c("black", "red", "blue"),
               legend = c("Sub_metering_1", "Sub_metering_2", "Sub_metering_3"),
               lwd=1, lty=c(1,1,1), bty = "n")

        plot(time_stamp, data$Voltage, type = "l", col = "black",
             xlab = "datetime", ylab = "Voltage", main = "")
        plot(time_stamp, data$Global_reactive_power, type = "l", col = "black",
             xlab = "datetime", ylab = "Global_reactive_power", main = "")

        dev.off()
}