Python学习笔记：Python常用标准库函数

math库：

>>> import math
>>> dir(math)
['__doc__', '__loader__', '__name__', '__package__', '__spec__', 'acos', 'acosh', 'asin', 'asinh', 'atan', 'atan2', 'atanh', 'ceil', 'copysign', 'cos', 'cosh', 'degrees', 'e', 'erf', 'erfc', 'exp', 'expm1', 'fabs', 'factorial', 'floor', 'fmod', 'frexp', 'fsum', 'gamma', 'gcd', 'hypot', 'inf', 'isclose', 'isfinite', 'isinf', 'isnan', 'ldexp', 'lgamma', 'log', 'log10', 'log1p', 'log2', 'modf', 'nan', 'pi', 'pow', 'radians', 'sin', 'sinh', 'sqrt', 'tan', 'tanh', 'tau', 'trunc']
>>> math.pi
3.141592653589793
>>> math.e
2.718281828459045
>>> help(math.ceil)
Help on built-in function ceil in module math:

ceil(...)
    ceil(x)
    
    Return the ceiling of x as an Integral.
    This is the smallest integer >= x.

>>> math.ceil(3.6)
4
>>> math.floor(3.6)
3
>>> math.pow(2,3)
8.0
>>> math.sqrt(4)
2.0
>>> math.degrees(3.14)
179.9087476710785
>>> math.radians(180)
3.141592653589793

os库：

import os
>>> os.getcwd()
'C:\\Users\\Administrator\\AppData\\Local\\Programs\\Python\\Python36-32'
>>> path='e:\\test'
>>> os.chdir(path)
>>> os.getcwd()
'e:\\test'
>>> os.rename('test.txt','test111.txt')
>>> os.remove('test111.txt')
>>> 

random库：

>>> import random
>>> random.choice(['C++','Java','Python'])
'Java'
>>> random.randint(1,100)
57
>>> random.randrange(0,10,2)
8
>>> random.random()
0.7906454183842933
>>> random.uniform(5,10)
7.753307224388041
>>> random.sample(range(100),10)
[91, 15, 67, 38, 55, 72, 62, 97, 51, 77]
>>> nums=[1001,1002,1003,1004,1005]
>>> random.shuffle(nums)
>>> nums
[1002, 1004, 1005, 1001, 1003]

datetime库：

import datetime
>>> dir(datetime)
['MAXYEAR', 'MINYEAR', '__builtins__', '__cached__', '__doc__', '__file__', '__loader__', '__name__', '__package__', '__spec__', 'date', 'datetime', 'datetime_CAPI', 'time', 'timedelta', 'timezone', 'tzinfo']
>>> from datetime import date
>>> date.today()
datetime.date(2018, 3, 7)
>>> from datetime import time
>>> tm=time(23,20,35)
>>> print(tm)
23:20:35
>>> from datetime import datetime
>>> dt=datetime.now()
>>> dt
datetime.datetime(2018, 3, 7, 15, 1, 7, 13107)
>>> print(dt.strftime('%a,%b %d %Y %H:%M'))
Wed,Mar 07 2018 15:01
>>> dt=datetime(2017,6,6,23,29)
>>> print(dt)
2017-06-06 23:29:00
ts=dt.timestamp()
>>> ts
1496762940.0
print(datetime.fromtimestamp(ts))
2017-06-06 23:29:00