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【python】常用内建模块

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标签:replace   tps   解析   def   creat   pass   mail   The   ret   

【datetime】

No1:

获取当前时间

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No2:

时区转换

>>> from datetime import datetime, timedelta, timezone
>>> tz_utc_8 = timezone(timedelta(hours=8)) # 创建时区UTC+8:00
>>> now = datetime.now()
>>> now
datetime.datetime(2015, 5, 18, 17, 2, 10, 871012)
>>> dt = now.replace(tzinfo=tz_utc_8) # 强制设置为UTC+8:00
>>> dt
datetime.datetime(2015, 5, 18, 17, 2, 10, 871012, tzinfo=datetime.timezone(datetime.timedelta(0, 28800)))

 

# 拿到UTC时间,并强制设置时区为UTC+0:00:
>>> utc_dt = datetime.utcnow().replace(tzinfo=timezone.utc)
>>> print(utc_dt)
2015-05-18 09:05:12.377316+00:00
# astimezone()将转换时区为北京时间:
>>> bj_dt = utc_dt.astimezone(timezone(timedelta(hours=8)))
>>> print(bj_dt)
2015-05-18 17:05:12.377316+08:00
# astimezone()将转换时区为东京时间:
>>> tokyo_dt = utc_dt.astimezone(timezone(timedelta(hours=9)))
>>> print(tokyo_dt)
2015-05-18 18:05:12.377316+09:00
# astimezone()将bj_dt转换时区为东京时间:
>>> tokyo_dt2 = bj_dt.astimezone(timezone(timedelta(hours=9)))
>>> print(tokyo_dt2)
2015-05-18 18:05:12.377316+09:00

【collections】

 No3:

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No4:

deque方便插入和删除

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OrderedDict有序

>>> from collections import OrderedDict
>>> d = dict([(a, 1), (b, 2), (c, 3)])
>>> d # dict的Key是无序的
{a: 1, c: 3, b: 2}
>>> od = OrderedDict([(a, 1), (b, 2), (c, 3)])
>>> od # OrderedDict的Key是有序的
OrderedDict([(a, 1), (b, 2), (c, 3)])

 

>>> od = OrderedDict()
>>> od[z] = 1
>>> od[y] = 2
>>> od[x] = 3
>>> list(od.keys()) # 按照插入的Key的顺序返回
[z, y, x]

 

 FIFO(先进先出)的dict

from collections import OrderedDict

class LastUpdatedOrderedDict(OrderedDict):

    def __init__(self, capacity):
        super(LastUpdatedOrderedDict, self).__init__()
        self._capacity = capacity

    def __setitem__(self, key, value):
        containsKey = 1 if key in self else 0
        if len(self) - containsKey >= self._capacity:
            last = self.popitem(last=False)
            print(remove:, last)
        if containsKey:
            del self[key]
            print(set:, (key, value))
        else:
            print(add:, (key, value))
        OrderedDict.__setitem__(self, key, value)

 

 Counter计数器

>>> from collections import Counter
>>> c = Counter()
>>> for ch in programming:
...     c[ch] = c[ch] + 1
...
>>> c
Counter({g: 2, m: 2, r: 2, a: 1, i: 1, o: 1, n: 1, p: 1})

【base64】

No5:

Base64是一种用64个字符来表示任意二进制数据的方法。

>>> import base64
>>> base64.b64encode(bbinary\x00string)
bYmluYXJ5AHN0cmluZw==
>>> base64.b64decode(bYmluYXJ5AHN0cmluZw==)
bbinary\x00string

 

>>> base64.b64encode(bi\xb7\x1d\xfb\xef\xff)
babcd++//
>>> base64.urlsafe_b64encode(bi\xb7\x1d\xfb\xef\xff)
babcd--__
>>> base64.urlsafe_b64decode(abcd--__)
bi\xb7\x1d\xfb\xef\xff

No6:

【struct】

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pack的第一个参数是处理指令,‘>I‘的意思是:

>表示字节顺序是big-endian,也就是网络序,I表示4字节无符号整数。

 【摘要算法】

No7:

摘要算法又称哈希算法、散列算法。它通过一个函数,把任意长度的数据转换为一个长度固定的数据串(通常用16进制的字符串表示)

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No8:

【hmac】

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No9:

【itertools】迭代

count()

>>> import itertools
>>> natuals = itertools.count(1)
>>> for n in natuals:
...     print(n)
...

数字无限增长,差点没爆掉

cycle()

>>> import itertools
>>> cs = itertools.cycle(ABC) # 注意字符串也是序列的一种
>>> for c in cs:
...     print(c)
...

ABC无限重复,又差点没爆掉

repeat()--限定重复次数

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chain()--可以把一组迭代对象串联起来,形成一个更大的迭代器:

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groupby()--把迭代器中相邻的重复元素挑出来放在一起:

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No10:

try:
    f = open(/path/to/file, r)
    f.read()
finally:
    if f:
        f.close()

可简化为

with open(/path/to/file, r) as f:
    f.read()

No11:

class Query(object):

    def __init__(self, name):
        self.name = name

    def __enter__(self):
        print(Begin)
        return self

    def __exit__(self, exc_type, exc_value, traceback):
        if exc_type:
            print(Error)
        else:
            print(End)

    def query(self):
        print(Query info about %s... % self.name)

使用

with Query(Bob) as q:
    q.query()

》》》》类可简化为

from contextlib import contextmanager

class Query(object):

    def __init__(self, name):
        self.name = name

    def query(self):
        print(Query info about %s... % self.name)

@contextmanager
def create_query(name):
    print(Begin)
    q = Query(name)
    yield q
    print(End)

使用

with create_query(Bob) as q:
    q.query()

No12:

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No13:

from contextlib import closing
from urllib.request import urlopen

with closing(urlopen(https://www.python.org)) as page:
    for line in page:
        print(line)

结果居然打印出整个html界面的代码

【GET】

No14:

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from urllib import request

req = request.Request(http://www.douban.com/)
req.add_header(User-Agent, Mozilla/6.0 (iPhone; CPU iPhone OS 8_0 like Mac OS X) AppleWebKit/536.26 (KHTML, like Gecko) Version/8.0 Mobile/10A5376e Safari/8536.25)
with request.urlopen(req) as f:
    print(Status:, f.status, f.reason)
    for k, v in f.getheaders():
        print(%s: %s % (k, v))
    print(Data:, f.read().decode(utf-8))

结果会返回豆瓣网的移动端页面

No15:

【POST】

模拟微博登陆

from urllib import request, parse

print(Login to weibo.cn...)
email = input(Email: )
passwd = input(Password: )
login_data = parse.urlencode([
    (username, email),
    (password, passwd),
    (entry, mweibo),
    (client_id, ‘‘),
    (savestate, 1),
    (ec, ‘‘),
    (pagerefer, https://passport.weibo.cn/signin/welcome?entry=mweibo&r=http%3A%2F%2Fm.weibo.cn%2F)
])

req = request.Request(https://passport.weibo.cn/sso/login)
req.add_header(Origin, https://passport.weibo.cn)
req.add_header(User-Agent, Mozilla/6.0 (iPhone; CPU iPhone OS 8_0 like Mac OS X) AppleWebKit/536.26 (KHTML, like Gecko) Version/8.0 Mobile/10A5376e Safari/8536.25)
req.add_header(Referer, https://passport.weibo.cn/signin/login?entry=mweibo&res=wel&wm=3349&r=http%3A%2F%2Fm.weibo.cn%2F)

with request.urlopen(req, data=login_data.encode(utf-8)) as f:
    print(Status:, f.status, f.reason)
    for k, v in f.getheaders():
        print(%s: %s % (k, v))
    print(Data:, f.read().decode(utf-8))

No16:

【Handler】

proxy_handler = urllib.request.ProxyHandler({http: http://www.example.com:3128/})
proxy_auth_handler = urllib.request.ProxyBasicAuthHandler()
proxy_auth_handler.add_password(realm, host, username, password)
opener = urllib.request.build_opener(proxy_handler, proxy_auth_handler)
with opener.open(http://www.example.com/login.html) as f:
    pass

No17:

【XML】

操作XML有两种方法:DOM和SAX。DOM会把整个XML读入内存,解析为树,因此占用内存大,解析慢,优点是可以任意遍历树的节点。SAX是流模式,边读边解析,占用内存小,解析快,缺点是我们需要自己处理事件。

正常情况下,优先考虑SAX,因为DOM实在太占内存。

from xml.parsers.expat import ParserCreate

class DefaultSaxHandler(object):
    def start_element(self, name, attrs):
        print(sax:start_element: %s, attrs: %s % (name, str(attrs)))

    def end_element(self, name):
        print(sax:end_element: %s % name)

    def char_data(self, text):
        print(sax:char_data: %s % text)

xml = r‘‘‘<?xml version="1.0"?>
<ol>
    <li><a href="/python">Python</a></li>
    <li><a href="/ruby">Ruby</a></li>
</ol>
‘‘‘

handler = DefaultSaxHandler()
parser = ParserCreate()
parser.StartElementHandler = handler.start_element
parser.EndElementHandler = handler.end_element
parser.CharacterDataHandler = handler.char_data
parser.Parse(xml)
L = []
L.append(r<?xml version="1.0"?>)
L.append(r<root>)
L.append(encode(some & data))
L.append(r</root>)
return ‘‘.join(L)

No18:

【HTMLParser】

from html.parser import HTMLParser
from html.entities import name2codepoint

class MyHTMLParser(HTMLParser):

    def handle_starttag(self, tag, attrs):
        print(<%s> % tag)

    def handle_endtag(self, tag):
        print(</%s> % tag)

    def handle_startendtag(self, tag, attrs):
        print(<%s/> % tag)

    def handle_data(self, data):
        print(data)

    def handle_comment(self, data):
        print(<!--, data, -->)

    def handle_entityref(self, name):
        print(&%s; % name)

    def handle_charref(self, name):
        print(&#%s; % name)

parser = MyHTMLParser()
parser.feed(‘‘‘<html>
<head></head>
<body>
<!-- test html parser -->
    <p>Some <a href=\"#\">html</a> HTML&nbsp;tutorial...<br>END</p>
</body></html>‘‘‘)

 

【python】常用内建模块

标签:replace   tps   解析   def   creat   pass   mail   The   ret   

原文地址:https://www.cnblogs.com/anni-qianqian/p/9239668.html

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