standardLibrary.py

"""
标准库概览
"""
# 操作系统接口-----------------------------
import os

os.getcwd()  # 返回当前的工作目录
os.chdir('/server/accesslogs')  # 修改当前的工作目录
os.system('mkdir today')  # 执行系统命令 mkdir
import shutil

shutil.copyfile('data.db', 'archive.db')
shutil.move('/build/executables', 'installdir')
# 文件通配符 ---------------------------------------------
# 用于从目录通配符搜索中生成文件列表
import glob

glob.glob('*.py')
# 命令行参数------------------------------------
import sys

print(sys.argv)
# 错误输出重定向和程序终止-------------------------------
# sys 还有 stdin，stdout 和 stderr 属性，即使在 stdout 被重定向时，后者也可以用于显示警告和错误信息。
sys.stderr.write('Warning, log file not found starting a new one\n')
# 字符串正则匹配-----------------------------------------------
import re
re.findall(r'\bf[a-z]*', 'which foot or hand fell fastest')
re.sub(r'(\b[a-z]+) \1', r'\1', 'cat in the the hat')
# 数学-----------------------------------------------
import math
math.cos(math.pi / 4)
math.log(1024, 2)
import random
random.choice(['apple', 'pear', 'banana'])
random.sample(range(100), 10)   # sampling without replacement
random.random()    # random float
random.randrange(6)
# 互联网-----------------------------------------------
from urllib.request import urlopen
for line in urlopen('http://tycho.usno.navy.mil/cgi-bin/timer.pl'):
    line = line.decode('utf-8')  # Decoding the binary data to text.
    if 'EST' in line or 'EDT' in line:  # look for Eastern Time
        print(line)



import smtplib
server = smtplib.SMTP('localhost')
server.sendmail('soothsayer@example.org', 'jcaesar@example.org',
"""To: jcaesar@example.org
...From: soothsayer@example.org
...
... Beware the Ides of March.
... """)
server.quit()
# 日期和时间-----------------------------------------------
from datetime import date
now = date.today()
print(now)
now.strftime("%m-%d-%y. %d %b %Y is a %A on the %d day of %B.")

# dates support calendar arithmetic
birthday = date(1964, 7, 31)
age = now - birthday
age.days
# 数据压缩
import zlib
s = b'witch which has which witches wrist watch'
len(s)
t = zlib.compress(s)
len(t)
zlib.decompress(t)
zlib.crc32(s)
# 性能度量
from timeit import Timer
Timer('t=a; a=b; b=t', 'a=1; b=2').timeit()
Timer('a,b = b,a', 'a=1; b=2').timeit()
# 测试模块
def average(values):
    """Computes the arithmetic mean of a list of numbers.

    >>> print(average([20, 30, 70]))
    40.0
    """
    return sum(values) / len(values)

import doctest
doctest.testmod()   # 自动验证嵌入测试
# unittest模块不像 doctest模块那么容易使用，不过它可以在一个独立的文件里提供一个更全面的测试集:

import unittest

class TestStatisticalFunctions(unittest.TestCase):

    def test_average(self):
        self.assertEqual(average([20, 30, 70]), 40.0)
        self.assertEqual(round(average([1, 5, 7]), 1), 4.3)
        self.assertRaises(ZeroDivisionError, average, [])
        self.assertRaises(TypeError, average, 20, 30, 70)

unittest.main() # Calling from the command line invokes all tests