pysal.viz.mapclassify.gadf(y, method='Quantiles', maxk=15, pct=0.8)[source]

Evaluate the Goodness of Absolute Deviation Fit of a Classifier Finds the minimum value of k for which gadf>pct

Parameters: y : array (n, 1) values to be classified method : {‘Quantiles, ‘Fisher_Jenks’, ‘Maximum_Breaks’, ‘Natrual_Breaks’} maxk : int maximum value of k to evaluate pct : float The percentage of GADF to exceed k : int number of classes cl : object instance of the classifier at k gadf : float goodness of absolute deviation fit

Notes

$GADF = 1 - \sum_c \sum_{i \in c} |y_i - y_{c,med}| / \sum_i |y_i - y_{med}|$

where $$y_{med}$$ is the global median and $$y_{c,med}$$ is the median for class $$c$$.

Examples

>>> import pysal.viz.mapclassify as mc
15

>>> qgadf2 = mc.classifiers.gadf(cal, pct = 0.2)