plot3.R

## Plot 3

library(lubridate)
library(dplyr)

# read in data
epc <- read.delim("data/household_power_consumption.txt", 
                  header = TRUE,
                  sep = ";")

epc$DateConcat <- paste(epc$Date, epc$Time, sep = "_")
epc$DateConcat <- dmy_hms(epc$DateConcat)

# format Date as Date class
epc$Date <- dmy(epc$Date)
epc$Time <- hms(epc$Time)


# subset to 2007-02-01, 2007-02-02
epcFeb <- epc[epc$Date == "2007-02-01"|
                epc$Date == "2007-02-02",]

# converting the other columns to numeric class
epcFeb$Sub_metering_1 <- as.numeric(epcFeb$Sub_metering_1)
epcFeb$Sub_metering_2 <- as.numeric(epcFeb$Sub_metering_2)
epcFeb$Sub_metering_3 <- as.numeric(epcFeb$Sub_metering_3)

png(filename = "plot3.png",
    width = 480,
    height = 480)
plot(epcFeb$DateConcat, epcFeb$Sub_metering_1, type = "S", col = "black",
     xlab = "",
     ylab = "Energy sub metering")
lines(epcFeb$DateConcat, epcFeb$Sub_metering_2, type = "S", col = "red")
lines(epcFeb$DateConcat, epcFeb$Sub_metering_3, type = "S", col = "blue")
legend("topright",
       c("Sub_metering_1", "Sub_metering_2", "Sub_metering_3"),
       col = c("black", "red", "blue"), lty = 1)
dev.off()