plot3.r

## loading file
require(sqldf)
file <- c("C:/Users/cgu018/Desktop/Analytics/Open Course/DS JHU/Explore Data Viz/Week 1/household_power_consumption.txt")
data_subset <- read.csv.sql(file, header = T, sep=";", sql = "select * from file 
where (Date == '1/2/2007' OR Date == '2/2/2007')" )

## deal with the question marks in the data an change to NA
data_subset[data_subset == "?"] <- NA 

## Convert date
data_subset$date_Time <- strptime(paste(data_subset$Date, data_subset$Time), "%d/%m/%Y %H:%M:%S")

## plot and save as png
plot(data_subset$date_Time,data_subset$Sub_metering_1,type="l",xlab=" ",ylab="Energy Sub Metering",ylim=c(0,40))
lines(data_subset$date_Time,data_subset$Sub_metering_2,ylim=c(0,40),col="red")
lines(data_subset$date_Time,data_subset$Sub_metering_3,ylim=c(0,40),col="blue")
legend("topright", col = c("black", "red", "blue"), lty = c("solid", "solid", "solid"), legend = names(data_subset[,7:9]))

dev.copy(png, "plot3.png", width =480, height=480)
dev.off()