python字母转数字 python 数字转字母

def changeNumToChar(self,s):
        '''
        把数字转换成相应的字符,1-->'A' 27-->'AA'
        '''
        a = [chr(i) for i in range(65, 91)]
        ss = ''
        b = []
        if s <= 26:
            b = [s]
        else:
            while s > 26:
                c = s // 26  # 商
                d = s % 26  # 余数
                b = b + [d]
                s = c
            b = b + [s]
        b.reverse()
        for i in b:
            ss = ss + a[i - 1]
        return ss