base_sp.py 文件源码

def cdf_to_ppf(self, data, params):
        '''
        Take the specific distributions fitted parameters and calculate the
        cdf. Apply the inverse normal distribution to the cdf to get the SPI 
        SPEI. This process is best described in Lloyd-Hughes and Saunders, 2002
        which is included in the documentation.

        '''

        # Calculate the CDF of observed precipitation on a given time scale
        cdf = self.distr.cdf(
            data, *params[:-2], loc=params[-2], scale=params[-1]
        )

        # Apply inverse normal distribution
        norm_ppf = scipy.stats.norm.ppf(cdf)

        return norm_ppf