廖雪峰Python学习笔记day12

骑猪看日落 2022-12-26 10:10 167阅读 0赞

学习笔记day11

  1. # python study day12
  3. # itertools 模块提供迭代功能处理函数，返回值是Iterator，用循环迭代计算输出
  4. # 1、count() 无限自然数序列迭代器
  5. # import itertools
  6. # ct = itertools.count(33)
  7. # for per in ct:
  8. # print(per) # 33 34 …
  9. # 2、cycle() 固定序列无限重复
  10. # import itertools
  11. # cc = itertools.cycle('abc')
  12. # for per in cc:
  13. # print(per) # a b c a b …
  14. # 3、repeat 元素无限重复，提供第二个参数限定重复次数
  15. # import itertools
  16. # re = itertools.repeat('ac', 3)
  17. # for per in re:
  18. # print(per) # ac ac ac
  19. # 3、chain() 串联迭代对象
  20. # import itertools
  21. # for per in itertools.chain('abc', 'xyz'):
  22. # print(per) # a b c x y z
  23. # 4、groupby() 将重复元素分组, 也可添加类似map中间处理函数
  24. # import itertools
  25. # for key, group in itertools.groupby('aAbBBcc', lambda c: c.lower()):
  26. # print(key, list(group))
  27. # # a ['a', 'A']
  28. # # b ['b', 'B', 'B']
  29. # # c ['c', 'c']
  30. # ' 计算pi的值 '
  31. # # step 1: 创建一个奇数序列: 1, 3, 5, 7, 9, ...
  32. # # step 2: 取该序列的前N项: 1, 3, 5, 7, 9, ..., 2*N-1.
  33. # # step 3: 添加正负符号并用4除: 4/1, -4/3, 4/5, -4/7, 4/9, ...
  34. # # step 4: 求和:
  35. # import itertools
  36. # # from functools import reduce
  37. # cc = itertools.count(1, 2)
  38. # List = []
  39. # for c in cc:
  40. # l = len(List)
  41. # if l > 1001:
  42. # break
  43. # List.append((4 * pow(-1, l) / c))
  44. # # result = reduce(lambda x, y: x+y, List)
  45. # result = sum(List)
  46. # print(result)
  48. # with open('/path/file', 'r') as f:… 语句，
  49. # 需要实现上下文__enter__和__exit__方法才能使用
  50. # class Query(object):
  51. # def __init__(self, name):
  52. # self.name = name
  53. # def __enter__(self):
  54. # print('Begin')
  55. # return self
  56. # def __exit__(self, exc_type, exc_value, traceback):
  57. # if exc_type:
  58. # print('error')
  59. # else:
  60. # print('end')
  61. # def query(self):
  62. # print('query info about %s ' % self.name)
  63. # with Query('Alice') as q:
  64. # q.query()
  65. # # Begin
  66. # # query info about Alice 
  67. # # end
  68. # contextlib标准库提供了更简便的写法 @contextmanager
  69. # from contextlib import contextmanager
  70. # class Query(object):
  71. # def __init__(self, name):
  72. # self.name = name
  73. # def query(self):
  74. # print('query info about %s ' % self.name)
  75. # @contextmanager
  76. # def create_query(name):
  77. # print('begin')
  78. # q = Query(name)
  79. # yield q # yield上半部分是__enter__,下半部分是__exit__
  80. # print('end')
  81. # from contextlib import contextmanager
  82. # @contextmanager
  83. # def tag(name):
  84. # print('<%s>' % name)
  85. # yield
  86. # print('</%s>' % name)
  87. # with tag('h1'):
  88. # print('\thello')
  89. # print('\tworld')
  90. # # <h1>
  91. # # hello
  92. # # world
  93. # # </h1>
  94. # @closing 可以使用closing()把对象变成上下文对象
  95. # from contextlib import closing
  96. # from urllib.request import urlopen
  97. # with closing(urlopen('https://www.pyhton.org')) as page:
  98. # for line in page:
  99. # print(line)
  101. # urllib 提供各种请求URL操作，可以通过请求头伪装成浏览器发出请求
  102. # GET 请求
  103. # from urllib import request
  104. # with request.urlopen('http://localhost:8888/maven-ssm/newShow') as f:
  105. # data = f.read()
  106. # print('status:', f.status, f.reason)
  107. # for k, v in f.getheaders():
  108. # print('%s %s' % (k, v))
  109. # print('data:', data.decode('utf-8'))
  110. # status: 200 
  111. # Content-Type application/json;charset=utf-8
  112. # Transfer-Encoding chunked
  113. # Date Fri, 04 Dec 2020 03:50:59 GMT
  114. # Connection close
  115. # data: "{\"code\":0,\"sta……\"}"
  116. # 在Request对象添加HTTP头，模拟iPhone6发送请求
  117. # from urllib import request
  118. # req = request.Request('http://www.douban.com/')
  119. # req.add_header('User-Agent', 'Mozilla/6.0 (iPhone; CPU iPhone OS 8_0'+
  120. # ' like Mac OS X) AppleWebKit/536.26 (KHTML, like Gecko) Version/8.0 '+
  121. # 'Mobile/10A5376e Safari/8536.25')
  122. # with request.urlopen(req) as f:
  123. # print('status:', f.status, f.reason)
  124. # for k, v in f.getheaders():
  125. # print('%s %s' % (k, v))
  126. # print('data:', f.read().decode('utf-8'))
  127. # # <meta charset="UTF-8">
  128. # # <title>豆瓣(手机版)</title>
  129. # # <meta name="google-site-verification" content="ok0wCgT……
  130. # Post 请求，把参数data以bytes形式传入
  131. # from urllib import request, parse
  132. # data = parse.urlencode([
  133. # ('username', 'email'),
  134. # ('password', 'passwd')
  135. # ])
  136. # req = request.Request('https://passport.weibo.cn/sso/login')
  137. # req.add_header('Origin', 'https://passport.weibo.cn')
  138. # req.add_header('User-Agent', 'Mozilla/6.0 (iPhone; CPU iPhone OS 8_0 '+
  139. # 'like Mac OS X) AppleWebKit/536.26 (KHTML, like Gecko) Version/8.0 '+
  140. # 'Mobile/10A5376e Safari/8536.25')
  141. # req.add_header('Referer', 'https://passport.weibo.cn/signin/login?'+
  142. # 'entry=mweibo&res=wel&wm=3349&r=http%3A%2F%2Fm.weibo.cn%2F')
  143. # with request.urlopen(req, data=login_data.encode('utf-8')) as f:
  144. # print('Status:', f.status, f.reason)
  145. # for k, v in f.getheaders():
  146. # print('%s: %s' % (k, v))
  147. # print('Data:', f.read().decode('utf-8'))
  148. # Handler 利用ProxyHandler 通过Proxy 访问网站
  149. # url = {'http': 'http://www.example.com:3128/'}
  150. # proxy_handler = urllib.request.ProxyHandler(url)
  151. # proxy_auth_handler = urllib.request.ProxyBasicAuthHandler()
  152. # proxy_auth_handler.add_password('realm', 'host', 'username', 'password')
  153. # opener = urllib.request.build_opener(proxy_handler, proxy_auth_handler)
  154. # with opener.open('http://www.example.com/login.html') as f:
  155. # pass
  156. # from urllib import request
  157. # import json
  158. # def fetch_data(url):
  159. # req = request.Request(url)
  160. # with request.urlopen(req) as f:
  161. # data = f.read()
  162. # return json.loads(data.decode('utf-8'))
  163. # URL = 'http://www.httpbin.org/get'
  164. # data = fetch_data(URL)
  165. # print(data)
  167. # XML解析。DOM:将整个XML读入内存、SAX:流模式，边读边解析(推荐)
  168. # SAX通过 start_element、end_element、char_data 函数解析xml
  169. # from xml.parsers.expat import ParserCreate
  170. # class DefaultSaxHandler(object):
  171. # def start_element(self, name, attrs):
  172. # print('sax:start_element: %s, attrs: %s' % (name, str(attrs)))
  173. # def end_element(self, name):
  174. # print('sax:end_element: %s' % name)
  175. # def char_data(self, text):
  176. # print('sax:char_data: %s' % text)
  177. # xml = r'''<?xml version="1.0"?>
  178. # <ol>
  179. # <li><a href="/python">Python</a></li>
  180. # <li><a href="/ruby">Ruby</a></li>
  181. # </ol>
  182. # '''
  183. # handler = DefaultSaxHandler()
  184. # parser = ParserCreate()
  185. # parser.StartElementHandler = handler.start_element
  186. # parser.EndElementHandler = handler.end_element
  187. # parser.CharacterDataHandler = handler.char_data
  188. # parser.Parse(xml)
  190. # HTMLParser 可以将html页面中的文本、图像等解析出来
  191. # from html.parser import HTMLParser
  192. # from html.entities import name2codepoint
  193. # class MyHTMLParser(HTMLParser):
  194. # def handle_starttag(self, tag, attrs):
  195. # print('<%s>' % tag)
  196. # def handle_endtag(self, tag):
  197. # print('</%s>' % tag)
  198. # def handle_startendtag(self, tag, attrs):
  199. # print('<%s/>' % tag)
  200. # def handle_data(self, data):
  201. # print(data)
  202. # def handle_comment(self, data):
  203. # print('<!--', data, '-->')
  204. # def handle_entityref(self, name):
  205. # print('&%s;' % name)
  206. # def handle_charref(self, name):
  207. # print('&#%s;' % name)
  208. # parser = MyHTMLParser()
  209. # parser.feed('''<html>
  210. # <head></head>
  211. # <body>
  212. # <!-- test html parser -->
  213. # <p>Some <a href=\"#\">html</a> HTML tutorial...<br>END</p>
  214. # </body></html>''')

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学习笔记day13

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