<23>python学习笔记——列表解析，字典解析，集合解析筛选元素

1 / 过滤掉列表中的负数

方式1：

from random import randint data = [1,5,-3,-6,8,0,9] list = [] for x in data: if x >=0: list.append(x) print(list) [1, 5, 8, 0, 9] 方式二 （filter()函数）

from random import randint data = [randint(-10,10) for _ in range(10)] data Out[9]: [7, 3, -4, 4, 10, -2, 6, 1, 1, -6] filter(lambda x:x>=0 ,data) Out[10]: <filter at 0x1c5eb204a58> lambda 是匿名函数

方式三 ——列表解析

data Out[18]: [7, 3, -4, 4, 10, -2, 6, 1, 1, -6] [x for x in data if x>=0] Out[19]: [7, 3, 4, 10, 6, 1, 1]

2 / dict 筛选出某些元素  ——字典解析

dict = {x : randint(60,100) for x in range(1,21)} dict Out[21]: {1: 92, 2: 85, 3: 100, 4: 91, 5: 78, 6: 62, 7: 80, 8: 83, 9: 71, 10: 73, 11: 73, 12: 74, 13: 74, 14: 84, 15: 87, 16: 68, 17: 70, 18: 70, 19: 85, 20: 67} {k: v for k,v in dict.items() if v >90} Out[24]: {1: 92, 3: 100, 4: 91} 3 / 集合解析

data Out[25]: [7, 3, -4, 4, 10, -2, 6, 1, 1, -6] s = set(data) s Out[27]: {-6, -4, -2, 1, 3, 4, 6, 7, 10} { x for x in s if x%3==0} Out[28]: {-6, 3, 6}