math.py 文件源码

def prctile(data, p_vals=[0, 25, 50, 75, 100], sorted_=False):
        """``prctile(data, 50)`` returns the median, but p_vals can
        also be a sequence.

        Provides for small samples or extremes IMHO better values than
        matplotlib.mlab.prctile or np.percentile, however also slower.

        """
        ps = [p_vals] if np.isscalar(p_vals) else p_vals

        if not sorted_:
            data = sorted(data)
        n = len(data)
        d = []
        for p in ps:
            fi = p * n / 100 - 0.5
            if fi <= 0:  # maybe extrapolate?
                d.append(data[0])
            elif fi >= n - 1:
                d.append(data[-1])
            else:
                i = int(fi)
                d.append((i + 1 - fi) * data[i] + (fi - i) * data[i + 1])
        return d[0] if np.isscalar(p_vals) else d