day12作业

from math import pi

# 1. 写一个生成式能够产生的数据为: 1, 4, 27, 256, 3125,…, 9**9
gen1 = (num ** num for num in range(1, 10))
for x in gen1:
    print(x)

# 2. 写一个生成式能够产生1-10中所有半径是偶数的圆的面积
gen2 = (pi * r ** 2 for r in range(1, 11) if r % 2 == 0)
for y in gen2:
    print(y)

# 3. 写一个生成式交换字段的键和值，产生一个新的字典
dict1 = {'a': 1, 'b': 2}


# dict2 = dict((dict1[key], key) for key in dict1)
# print(dict2)


def i(n):
    for key in dict1:
        yield (dict1[key], key)


print(dict(i(dict1)))