hmm_sparsity.py 文件源码

def _gini(self, array):
        """Calculate the Gini coefficient of a numpy array."""
        # https://github.com/oliviaguest/gini
        # based on bottom eq:
        # http://www.statsdirect.com/help/generatedimages/equations/equation154.svg
        # from:
        # http://www.statsdirect.com/help/default.htm#nonparametric_methods/gini.htm
        # All values are treated equally, arrays must be 1d:
        array = array.flatten()
        if np.amin(array) < 0:
            # Values cannot be negative:
            array -= np.amin(array)
        # Values cannot be 0:
        array += 0.0000001
        # Values must be sorted:
        array = np.sort(array)
        # Index per array element:
        index = np.arange(1,array.shape[0]+1)
        # Number of array elements:
        n = array.shape[0]
        # Gini coefficient:
        return ((np.sum((2 * index - n  - 1) * array)) / (n * np.sum(array)))