Source code for complex_systems.spatial.kernel_density_geo

#!/usr/bin/python
# -*- coding: utf-8 -*-

# -------------------------------------------------------------------------------
# Copyright (c) 2012 Vincent Gauthier.
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__author__ = """\n""".join(['Vincent Gauthier'])


def kernel_density_geo(X_data, Y_data, bin_size_x=10, bin_size_y=10):
    '''
    more information about the `Kernel density estimation <http://en.wikipedia.org/wiki/Kernel_density_estimation>`_
    '''
    import scipy.stats as stats
    import numpy as N
    
    #Format teh entry to make sure it is a colum vector 
    X_data = N.transpose([X_data.ravel()])
    Y_data = N.transpose([Y_data.ravel()])
    pos = N.append(X_data,Y_data,axis=1)

    kde = stats.kde.gaussian_kde(pos.T)

    X_flat = N.linspace(pos[:,0].min(),pos[:,0].max(),bin_size_x)
    Y_flat = N.linspace(pos[:,1].min(),pos[:,1].max(),bin_size_y)

    X,Y = N.meshgrid(X_flat,Y_flat)
    
    grid_coords =N.append(X.reshape(-1,1),Y.reshape(-1,1),axis=1)
    Z = kde(grid_coords.T)
    Z = Z.reshape(bin_size_x,bin_size_y)

    return grid_coords,Z