float[] volume;
  float minVolume, maxVolume;

  int[] year;

  float X1, X2, Y1, Y2;

  PFont legendFont = createFont("SansSerif", 20);

  void setup() {
    String[] lines = loadStrings("USPSData.txt");
   
     volume = new float[lines.length];
     year = new int[lines.length];

     int j = 0;
     for (int i=0; i<lines.length; i++) {
       String[] pieces = split(lines[i], ",");
       
       // get the data
       volume[i] = float(pieces[1].substring(1, pieces[1].length()-1));
       year[i] = int(pieces[0]);
     }
     println("Data Loaded:");

     minVolume = min(volume);
     maxVolume = max(volume);
     println(minVolume);
     println(maxVolume);
     // drawing setup
     size(800, 400);
   
     // plot rectangle
     X1 = 120;
     X2 = width-30;
     Y1 = 50;
     Y2 = height - Y1;
     
     smooth();
     textFont(legendFont);
   
   } // setup

  void draw() {
    background(0);

    rectMode(CORNERS);
    noStroke();
    fill(255);
    rect(X1, Y1, X2, Y2);

    stroke(0);
    fill(200);
    drawGraph(volume);

    // draw legend
    // title & Source info
    fill(255);
    textSize(18);
    textAlign(LEFT);
    text("US Postal Service First Class Mail Volume (in Billions)", X1,
        Y1 - 10);
    textSize(10);
    textAlign(RIGHT, BOTTOM);
    text("USPS.gov", width - 10, height - 10);

    // axis labels
    drawXLabels();
    drawYLabels();
  } // draw

  void drawGraph(float[] data) {
    beginShape();
    for (int i = 0; i < data.length; i++) {
      float x = map(i, 0, data.length - 1, X1, X2);
      float y = map(data[i], 0, maxVolume, Y2, Y1);
      vertex(x, y);
    }
    vertex(X2, Y2);
    vertex(X1, Y2);
    endShape(CLOSE);
  } // drawGraph

  void drawXLabels() {
    fill(255);
    textSize(10);
    textAlign(CENTER);

    for (int i = 0; i < year.length; i += 10) {
      float x = map(i, 0, year.length, X1, X2);
      text(year[i], x, Y2 + 10);
      stroke(0);
      line(x, Y1, x, Y2);
    }
    textSize(18);
    textAlign(CENTER, TOP);
    text("Year", width / 2, Y2 + 10);
  } // drawXLabels

  void drawYLabels() {
    fill(255);
    textSize(10);
    textAlign(RIGHT);

    for (float i = 0; i <= maxVolume; i += 10000) {
      float y = map(i, 0, maxVolume, Y2, Y1);
      text(floor(i / 1000), X1 - 10, y);
      line(X1, y, X2, y);
    }
    textSize(18);
    text("Volume", X1 - 40, height / 2);
  }

  void mouseClicked() {
    save("USPSFirstClassColume.tiff");
  }