import string import random letters_num= random.randint(1,8) numbers_num = 9-letters_num pass_wd = " " for i in range(9):     if random.randint(0,1):#0和1随机获取，1获取字母，0获取数字         pass_wd+=string.ascii

s = "a1b2c3b4d577777aab" non_digit_list = [] for i in s:     if i not in "0123456789":         non_digit_list.append(i) print("".join(non_digit_list))   输出结果： >>> print("".join(non_digit_list)) ab

方法一： # encoding=utf-8 d = {'a':1,"b":2,"c":3,"d":4,"e":4} max_value= d['a'] result = [] for k,v in d.items():     print(k,v)     if v > max_value:         max_value =v         result = []         r

# encoding=utf-8  #倒序 s = "I am a boy!" result=[] for i in s.split()[::-1]:     result.append(i[0]) print(result) 输出结果： ['b', 'a', 'a', 'I']