plot3.R

#####################################
### Data input and manipulation #####
#####################################



setwd("~/R/courseraEDA/Project1")

data <- read.table("power.txt",  	#pre-extracted data for specified dates with grep
	comment.char="#",sep=";",
	stringsAsFactors = FALSE,
	col.names = c("date","time","active","reactive","voltage","intensity","sm1","sm2","sm3"))


	 
data$date <- as.Date(data$date,format="%d/%m/%Y")            #convert date to Date class
dateTime <- paste(data$date,data$time,sep=",")
newDateTime <- strptime(dateTime,format='%Y-%m-%d,%H:%M:%S')	#convert date & time to POSIXlt


#####################################
### Plot 3 ##########################
#####################################

png("plot3.png",    				# create PNG for the heat map        
  	width = 480,        			# dimensions in pixels
  	height = 480,
  ) 
plot(newDateTime,data$sm1, type = "l",		#black line graph sm1
	ylab ="Energy sub metering",xlab= "", #label axes
	)

lines(newDateTime,data$sm2, type = "l",		#red line graph sm2
	col="red")
lines(newDateTime,data$sm3, type = "l",		#blue line graph sm3
	col="blue")
legendTxt <- c("sub_metering_1","sub_metering_2","sub_metering_3")
legend("topright",legendTxt,col = c("black", "red", "blue"),lty=1)

dev.off()               			# close the PNG device