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++) {
   if (lines[i].charAt(0) == '#') continue;
   String[] pieces = split(lines[i], ",");
   
   // get the closing price of stock, and month
   volume[i] = float(pieces[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");
}