plot3.R

estimateSize <- function() {
  2075259 * 9 -> totalCells
  totalCells * 8 -> totalBytes
  totalBytes / 1024
}

getData <- function() {
  # Read in the Table
  read.table("household_power_consumption.txt", header = TRUE, sep = ";", na.strings = "?", stringsAsFactors = FALSE)
  #return myData
}

plot3 <- function() { 
  oldpar <- par()
  mfrow=c(1,1)
  # if the table isn't already in memory, read it in
  ### This isn't working. 'exists(myData)' throws and error when it doesn't exist. Which doesn't make any sense
  myData <- data.frame()
  if(nrow(myData) == 0) {
    myData <- getData()
  }
  # convert existing Date and Time columns into POSIXct objects
  # Store in new column, so as to not mess with the original dataset
  dmy_hms(paste(myData$Date, myData$Time, sep = " ")) -> myData$newDate
  
  #  apply(myData[, 3-9], 2, as.numeric)
  startDate <- ymd_hms("2007-02-01 00:00:00")
  endDate <- ymd_hms("2007-02-02 23:59:59")
  myData[myData$newDate >= startDate & myData$newDate <= endDate, ] -> subsetData
  #message(nrow(subsetData))
  #head(subsetData)
  

  ## Plot 3
## Not sure if this is necessary anymore
  maxY1 <- max(subsetData$Sub_metering_1)
  maxY2 <- max(subsetData$Sub_metering_2)
  maxY3 <- max(subsetData$Sub_metering_3)
  maxY <- max(c(maxY1, maxY2, maxY3))
  png("plot3.png")
  plot(subsetData$newDate, subsetData$Sub_metering_1, type = "n", xlab = "", ylab = "Energy sub metering", ylim = c(0, maxY))
  with(subsetData, lines(newDate, Sub_metering_1, col = "black"))
  with(subsetData, lines(newDate, Sub_metering_2, col = "red"))
  with(subsetData, lines(newDate, Sub_metering_3, col = "blue"))
  legend("topright", names(subsetData)[7:9], lty=c(1,1,1), lwd=c(1,1,1),col=c("black","red", "blue"))

  ##title(main = "Sub metering 1-3")
  dev.off()
  
    
    # rm(myData)
    par(oldpar)
}