ch.epfl.scapetoad
Class CartogramGastner

java.lang.Object
  ch.epfl.scapetoad.CartogramGastner

public class CartogramGastner
extends java.lang.Object

This class implements Gastner's diffusion algorithm.

Field Summary

CartogramWizard	mCartogramWizard
int	mProgressEnd
int	mProgressStart Attributes for the computation progress bar.
java.lang.String	mProgressText

Constructor Summary

CartogramGastner(CartogramGrid grid)
The constructor takes the cartogram grid which contains the density values.

Method Summary

void	compute(int gridSize) Starts the cartogram computation using the given grid size.
static double	erf(double value) Our wrapper function for the Jakarta Commons Math Erf.erf function.
void	gaussianBlur() Performs au Gaussian blur on the density grid.
boolean	newt2(double h, double[] ptappr, double xguess, double yguess, int j, int k)
void	writeToShapefile(java.lang.String shapefile) Writes the grid into the specified shape file.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

mProgressStart

public int mProgressStart

Attributes for the computation progress bar.

mProgressEnd

public int mProgressEnd

mProgressText

public java.lang.String mProgressText

mCartogramWizard

public CartogramWizard mCartogramWizard

Constructor Detail

CartogramGastner

public CartogramGastner(CartogramGrid grid)

The constructor takes the cartogram grid which contains the density values.

Method Detail

compute

public void compute(int gridSize)
             throws java.lang.InterruptedException

Starts the cartogram computation using the given grid size.

Parameters:

gridSize - the size of the grid used for computation. The grid size must be a power of 2.

Throws:

java.lang.InterruptedException

gaussianBlur

public void gaussianBlur()

Performs au Gaussian blur on the density grid.

newt2

public boolean newt2(double h,
                     double[] ptappr,
                     double xguess,
                     double yguess,
                     int j,
                     int k)

erf

public static double erf(double value)

Our wrapper function for the Jakarta Commons Math Erf.erf function. For values <= -4 or >= 4, we return -1 or 1 directly, without computation. Erf.erf raises too often an exception for failing convergence.

writeToShapefile

public void writeToShapefile(java.lang.String shapefile)

Writes the grid into the specified shape file.

Parameters:

shapefile - the path to the shape file.