列表数组集合解析

from random import randint

a = [randint(-10, 10) for _ in range(10)]  # -10 -- 10 随机生成长度为10的列表
# print(a)
# 赛选出正数
# 方案一：
# 速度最慢
z_list = []
for i in a:
    if i >= 0:
        z_list.append(i)
print(z_list)
# 方案二: 速度中
p = filter(lambda x: x >= 0, a)
print(list(p))
print(type(p))
# 方案三：速度最
l = [x for x in a if x >= 0]  # 列表解析
print(l)

# 字典解析
t_dict = {k: randint(1, 100) for k in range(1, 21)}  # 随机生成一个字典
print(t_dict)
s_dict = {k: v for k, v in t_dict.items() if v >= 60}
print(s_dict)

# 集合解析
t_set = {x for x in range(1, 21) if x % 3 == 0}
print(t_set)


# 匿名函数lambda
s = lambda x:x*x
print(s(2))
# map 方法
b_list = [1,2,3,4]
mm = map(lambda x:x if x >2 else None,b_list)
print(list(mm))