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# graph of book sales on Amazon

Michael Kenning
Greenhorn
Posts: 3
I need to make a graph in Java that will output data about book sales on Amazon. Help, please!?
I have found the following base program from Ian Darwin (http://www.darwinsys.com/ ):

package org.me.mylib;

/**
*
* @author Ian Darwin
*/
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.geom.Point2D;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class Grapher extends JPanel {

private static final long serialVersionUID = -1813143391310613248L;

/** Multiplier for range to allow room for a border */
public final static double BORDERFACTOR = 1.1f;

/** The list of Point points. */
protected List<Point2D> data;

/** The minimum and maximum X values */
protected double minx = Integer.MAX_VALUE, maxx = Integer.MIN_VALUE;
/** The minimum and maximum Y values */
protected double miny = Integer.MAX_VALUE, maxy = Integer.MIN_VALUE;
/** The range of X and Y values */
protected double xrange, yrange;

public Grapher() {
data = new ArrayList<Point2D>();
figure();
}

/** Set the list data from a list of Strings, where the
* x coordinate is incremented automatically, and the y coordinate
* is made from the String in the list.
*/
public void setListDataFromYStrings(List<String> newData) {
data.clear();
for (int i=0; i < newData.size(); i++) {
Point2D p = new Point2D.Double();
p.setLocation(i, java.lang.Double.parseDouble(newData.get…
}
figure();
}

/** Set the list from an existing List, as from GraphReader.read() */
public void setListData(List<Point2D> newData) {
data = newData;
figure();
}

/** Compute new data when list changes */
private void figure() {
// find min & max
for (int i=0 ; i < data.size(); i++) {
Point2D d = (Point2D)data.get(i);
if (d.getX() < minx) minx = d.getX();
if (d.getX() > maxx) maxx = d.getX();
if (d.getY() < miny) miny = d.getY();
if (d.getY() > maxy) maxy = d.getY();
}

// Compute ranges
xrange = (maxx - minx) * BORDERFACTOR;
yrange = (maxy - miny) * BORDERFACTOR;
//Debug.println("range", "minx,x,r = " + minx +' '+ maxx +' '+ xrange);
//Debug.println("range", "miny,y,r = " + miny +' '+ maxy +' '+ yrange);
}

/** Called when the window needs painting.
* Computes X and Y range, scales.
*/
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Dimension s = getSize();
if (data.size() < 2) {
g.drawString("Insufficient data: " + data.size(), 10, 40);
return;
}

// Compute scale factors
double xfact = s.width / xrange;
double yfact = s.height / yrange;

// Scale and plot the data
for (int i=0 ; i < data.size(); i++) {
Point2D d = (Point2D)data.get(i);
double x = (d.getX() - minx) * xfact;
double y = (d.getY() - miny) * yfact;
Debug.println("point", "AT " + i + " " + d + "; " +
"x = " + x + "; y = " + y);
// Draw a 5-pixel rectangle centered, so -2 both x and y.
// AWT numbers Y from 0 down, so invert:
g.drawRect(((int)x)-2, s.height-2-(int)y, 5, 5);
}
}
[color=darkblue]
I need to add more detail to get it to show lines and there are some mistakes because of my changes in the program. Can anybody help me?

Rob Spoor
Sheriff
Posts: 20531
54