三小时快速入门Python终结篇--其他模块导入

1、数学模块math

 1 # 可以直接引用其它模块
 2 import math
 3 print(math.sqrt(16))  # => 4
 4 # 也可以引用模块中的函数
 5 from math import ceil, floor
 6 print(ceil(3.7))  # => 4.0
 7 print(floor(3.7))   # => 3.0
 8 
 9 # 你可以引用一个模块中的所有函数
10 # 警告：这是不推荐的
11 from math import *
12 # 可以给模块起个简短的别名
13 import math as m
14 math.sqrt(16) == m.sqrt(16)   # => True
15 # you can also test that the functions are equivalent
16 from math import sqrt
17 math.sqrt == m.sqrt == sqrt  # => True
18 # Python modules are just ordinary python files. You
19 # can write your own, and import them. The name of the
20 # module is the same as the name of the file.
21 # You can find out which functions and attributes
22 # defines a module.
23 import math
24 dir(math)

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