2019-11-19-Python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
g1 = (n ** n for n in range(1, 10))
for num in g1:
    print(num)
# 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
g2 = (pi * r ** 2 for r in range(1, 11) if r & 1 == 0)
for num in g2:
    print(num)


# 3. 写一个生成式交换字典的键和值，产生一个新的字典

def exchange_dic(dic1):
    dic2 = {}
    for key in dic1:
        dic2[dic1[key]] = key
    yield dic2


g3 = exchange_dic({'a': 1, 'b': 2})
print(next(g3))

dict1 = {'a': 1, 'b': 2}
dict2 = dict((dict1[key], key) for key in dict1)
print(dict2)