python实现求和、计数、最大最小值、平均值、中位数、标准偏差、百分比。

import sys class Stats:     def __init__(self, sequence):        # sequence of numbers we will PRocess        # convert all items to floats for numerical processing        self.sequence = [float(item) for item in sequence]     def sum(self):        if len(self.sequence) < 1:            return None        else:            return sum(self.sequence)     def count(self):        return len(self.sequence)     def min(self):        if len(self.sequence) < 1:            return None        else:            return min(self.sequence)     def max(self):        if len(self.sequence) < 1:            return None        else:            return max(self.sequence)     def avg(self):        if len(self.sequence) < 1:            return None        else:            return sum(self.sequence) / len(self.sequence)         def median(self):        if len(self.sequence) < 1:            return None        else:            self.sequence.sort()            return self.sequence[len(self.sequence) // 2]     def stdev(self):        if len(self.sequence) < 1:            return None        else:            avg = self.avg()            sdsq = sum([(i - avg) ** 2 for i in self.sequence])            stdev = (sdsq / (len(self.sequence) - 1)) ** .5            return stdev     def percentile(self, percentile):        if len(self.sequence) < 1:            value = None        elif (percentile >= 100):            sys.stderr.write('ERROR: percentile must be < 100.  you supplied: %s/n'% percentile)            value = None        else:            element_idx = int(len(self.sequence) * (percentile / 100.0))            self.sequence.sort()            value = self.sequence[element_idx]        return value