plot3.R

### 3rd plot
fileUrl <- "https://d396qusza40orc.cloudfront.net/exdata%2Fdata%2Fhousehold_power_consumption.zip"

download.file(fileUrl, destfile = "gastoElec.zip")

unzip("gastoElec.zip")

tbl <- read.csv("household_power_consumption.txt", header = T,
               sep = ';', na.strings = "?", nrows = 2075259,
               check.names = F, stringsAsFactors = F,
               quote = '\"')

library(dplyr)

tbl_1_2 <- filter(tbl, Date == "1/2/2007" | Date == "2/2/2007")

rm(tbl)

tbl_1_2[, "Date"] <- as.Date(tbl_1_2[, "Date"], format = "%d/%m/%Y")

tbl_1_2$Datetime <- as.POSIXct(paste(tbl_1_2$Date, tbl_1_2$Time))

with(tbl_1_2, {
    plot(Sub_metering_1 ~ Datetime, type = "l",
         ylab = "Energy sub metering", xlab = "")
    lines(Sub_metering_2 ~ Datetime, col = "Red")
    lines(Sub_metering_3 ~ Datetime, col = "Blue")   
})

legend("topright", col = c("black", "red", "blue"), 
      lty = 1, lwd = 2, pt.cex=1, cex=0.5,
      legend = c("Sub_metering_1", "Sub_metering_2", 
                 "Sub_metering_3")
)