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缘由：

整理总结一下最近在编码过程中遇到的一些Python知识点，方便以后快速参考、学习。（其实很多知识点之前都或多或少的整理过，但时间一长、很久没用之后就忘了，只能通过不断的使用、整理来加强记忆）

正文：

参考解答：

1、如何将文件中的内容（简单快速地）按行读入并放入set

set(line.strip() for line in open('filename.txt'))

即，如果没有什么复杂的判断、过滤条件，利用列表推导式即可快速实现（并不适合非常大的文件）。

• https://stackoverflow.com/questions/874017/python-load-words-from-file-into-a-set
• https://stackoverflow.com/questions/3277503/how-to-read-a-file-line-by-line-into-a-list

2、Python中的三元操作符

a = 1
b = 2
h = ""
print(h)
h = "变量1" if a>b else "变量2"
print(h)

is_fat = True
state = "fat" if is_fat else "not fat"

• https://www.cnblogs.com/mywood/p/7416893.html
• https://eastlakeside.gitbooks.io/interpy-zh/content/ternary_operators/ternary_operators.html

3、如何快速从URL中提取主机名等信息？

>>> from urlparse import urlparse
>>> o = urlparse('http://www.cwi.nl:80/%7Eguido/Python.html')
>>> o
ParseResult(scheme='http', netloc='www.cwi.nl:80', path='/%7Eguido/Python.html', params='', query='', fragment='')
>>> o.scheme
'http'
>>> o.netloc
'www.cwi.nl:80'

• https://pymotw.com/2/urlparse/
• https://docs.python.org/2/library/urlparse.html
• https://stackoverflow.com/questions/9626535/get-protocol-host-name-from-url
• https://stackoverflow.com/questions/9530950/parsing-hostname-and-port-from-string-or-url/17769986

4、如何判断某个IP是否为内网地址

方法一：借助 IPy 模块
方法二：Python 3提供了一个 ipaddress 的内置模块
方法三：用正则进行判断
方法四：用内置的unpack和socket模块进行判断

from struct import unpack
from socket import AF_INET, inet_pton

def lookup(ip):
    f = unpack('!I',inet_pton(AF_INET,ip))[0]
    private = (
        [ 2130706432, 4278190080 ], # 127.0.0.0, 255.0.0.0 http://tools.ietf.org/html/rfc3330
        [ 3232235520, 4294901760 ], # 192.168.0.0, 255.255.0.0 http://tools.ietf.org/html/rfc1918
        [ 2886729728, 4293918720 ], # 172.16.0.0, 255.240.0.0 http://tools.ietf.org/html/rfc1918
        [ 167772160, 4278190080 ], # 10.0.0.0, 255.0.0.0 http://tools.ietf.org/html/rfc1918
    ) 
    for net in private:
        if (f & net[1]) == net[0]:
            return True
    return False

# example
print(lookup("127.0.0.1"))
print(lookup("192.168.10.1"))
print(lookup("10.10.10.10"))
print(lookup("172.17.255.255"))
# outputs True True True True

5、如何根据域名/主机名获取对应的IP

import socket
print socket.gethostbyname('stackexchange.com')

• https://stackoverflow.com/questions/34573322/read-a-list-of-hostnames-and-resolve-to-ip-addresses
• https://docs.python.org/2/library/socket.html#socket.gethostbyname

6、如何在解析域名的IP时使用自己设定的DNS服务器地址

from dns import resolver

res = resolver.Resolver()
res.nameservers = ['8.8.8.8']

answers = res.query('stackexchange.com')
for rdata in answers:
    print (rdata.address)

• https://github.com/rthalley/dnspython
• https://stackoverflow.com/questions/34793061/socket-resolve-dns-with-specific-dns-server

7、Python中如何将 时:分:秒 的格式转换成 xx 秒？

# 方法一：借助 datetime 模块
>>> import datetime
>>> import time
>>> x = time.strptime('00:01:00,000'.split(',')[0],'%H:%M:%S')
>>> datetime.timedelta(hours=x.tm_hour,minutes=x.tm_min,seconds=x.tm_sec).total_seconds()
60.0

# 方法二：累加计算
timestr = '00:04:23'
ftr = [3600,60,1]
sum([a*b for a,b in zip(ftr, map(int,timestr.split(':')))])

• https://stackoverflow.com/questions/10663720/converting-a-time-string-to-seconds-in-python
• https://stackoverflow.com/questions/6402812/how-to-convert-an-hmmss-time-string-to-seconds-in-python

8、Python中如何将 DD/MM/YYYY HH:MM:SS 等格式的日期字符串转换成 xx 秒的形式？

>>> import datetime
>>> import time
>>> s = "16/08/2013 09:51:43"
>>> d = datetime.datetime.strptime(s, "%d/%m/%Y %H:%M:%S")
>>> time.mktime(d.timetuple())
1376632303.0

• https://stackoverflow.com/questions/18269888/convert-datetime-format-into-seconds
• https://stackoverflow.com/questions/2775864/python-create-unix-timestamp-five-minutes-in-the-future/16307378#16307378
• https://docs.python.org/2/library/time.html#time.mktime

9、Python中如何将包含中文的json/dict进行格式化输出？

import json
your_json = '["foo", {"bar":["你好", null, 1.0, 2]}]' # json array string
parsed = json.loads(your_json) # type(parsed) == list

print(parsed)
# [u'foo', {u'bar': [u'\u4f60\u597d', None, 1.0, 2]}]
print(json.dumps(parsed, indent=4, ensure_ascii=False))
# [
# "foo",
# {
# "bar": [
# "\u4f60\u597d",
# null,
# 1.0,
# 2
# ]
# }
# ]
print(json.dumps(parsed, indent=4, ensure_ascii=False))
# [
# "foo",
# {
# "bar": [
# "你好",
# null,
# 1.0,
# 2
# ]
# }
# ]

• https://stackoverflow.com/questions/12943819/how-to-prettyprint-a-json-file
• https://docs.python.org/2/library/json.html#json.dumps

参考链接：

• 如上

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