爬蟲必備—BeautifulSoup


BeautifulSoup是一個模塊,該模塊用於接收一個HTML或XML字符串,然后將其進行格式化,之后便可以使用他提供的方法進行快速查找指定元素,從而使得在HTML或XML中查找指定元素變得簡單。

 1 from bs4 import BeautifulSoup
 2  
 3 html_doc = """
 4 <html><head><title>The Dormouse's story</title></head>
 5 <body>
 6 asdf
 7     <div class="title">
 8         <b>The Dormouse's story總共</b>
 9         <h1>f</h1>
10     </div>
11 <div class="story">Once upon a time there were three little sisters; and their names were
12     <a  class="sister0" id="link1">Els<span>f</span>ie</a>,
13     <a href="http://example.com/lacie" class="sister" id="link2">Lacie</a> and
14     <a href="http://example.com/tillie" class="sister" id="link3">Tillie</a>;
15 and they lived at the bottom of a well.</div>
16 ad<br/>sf
17 <p class="story">...</p>
18 </body>
19 </html>
20 """
21  
22 soup = BeautifulSoup(html_doc, features="lxml")
23 # 找到第一個a標簽
24 tag1 = soup.find(name='a')
25 # 找到所有的a標簽
26 tag2 = soup.find_all(name='a')
27 # 找到id=link2的標簽
28 tag3 = soup.select('#link2')
簡單示例

1. name,標簽名稱

1 # tag = soup.find('a')
2 # name = tag.name # 獲取
3 # print(name)
4 # tag.name = 'span' # 設置
5 # print(soup)

2. attr,標簽屬性

1 # tag = soup.find('a')
2 # attrs = tag.attrs    # 獲取
3 # print(attrs)
4 # tag.attrs = {'ik':123} # 設置
5 # tag.attrs['id'] = 'iiiii' # 設置
6 # print(soup)

3. children,所有子標簽

1 # body = soup.find('body')
2 # v = body.children

4. descendants,所有子子孫孫標簽

1 # body = soup.find('body')
2 # v = body.descendants

5. clear,將標簽的所有子標簽全部清空(保留標簽名)

1 # tag = soup.find('body')
2 # tag.clear()
3 # print(soup)

6. decompose,遞歸的刪除所有的標簽

1 # body = soup.find('body')
2 # body.decompose()
3 # print(soup)

7. extract,遞歸的刪除所有的標簽,並獲取刪除的標簽

1 # body = soup.find('body')
2 # v = body.extract()
3 # print(soup)

8. decode,轉換為字符串(含當前標簽);decode_contents(不含當前標簽)

1 # body = soup.find('body')
2 # v = body.decode()
3 # v = body.decode_contents()
4 # print(v)

9. encode,轉換為字節(含當前標簽);encode_contents(不含當前標簽)

1 # body = soup.find('body')
2 # v = body.encode()
3 # v = body.encode_contents()
4 # print(v)

10. find,獲取匹配的第一個標簽

1 # tag = soup.find('a')
2 # print(tag)
3 # tag = soup.find(name='a', attrs={'class': 'sister'}, recursive=True, text='Lacie')
4 # tag = soup.find(name='a', class_='sister', recursive=True, text='Lacie')
5 # print(tag)

11. find_all,獲取匹配的所有標簽

 1 # tags = soup.find_all('a')
 2 # print(tags)
 3  
 4 # tags = soup.find_all('a',limit=1)
 5 # print(tags)
 6  
 7 # tags = soup.find_all(name='a', attrs={'class': 'sister'}, recursive=True, text='Lacie')
 8 # # tags = soup.find(name='a', class_='sister', recursive=True, text='Lacie')
 9 # print(tags)
10  
11  
12 # ####### 列表 #######
13 # v = soup.find_all(name=['a','div'])
14 # print(v)
15  
16 # v = soup.find_all(class_=['sister0', 'sister'])
17 # print(v)
18  
19 # v = soup.find_all(text=['Tillie'])
20 # print(v, type(v[0]))
21  
22  
23 # v = soup.find_all(id=['link1','link2'])
24 # print(v)
25  
26 # v = soup.find_all(href=['link1','link2'])
27 # print(v)
28  
29 # ####### 正則 #######
30 import re
31 # rep = re.compile('p')
32 # rep = re.compile('^p')
33 # v = soup.find_all(name=rep)
34 # print(v)
35  
36 # rep = re.compile('sister.*')
37 # v = soup.find_all(class_=rep)
38 # print(v)
39  
40 # rep = re.compile('http://www.oldboy.com/static/.*')
41 # v = soup.find_all(href=rep)
42 # print(v)
43  
44 # ####### 方法篩選 #######
45 # def func(tag):
46 # return tag.has_attr('class') and tag.has_attr('id')
47 # v = soup.find_all(name=func)
48 # print(v)
49  
50  
51 # ## get,獲取標簽屬性
52 # tag = soup.find('a')
53 # v = tag.get('id')
54 # print(v)
View Code

12. has_attr,檢查標簽是否具有該屬性

1 # tag = soup.find('a')
2 # v = tag.has_attr('id')
3 # print(v)

13. get_text,獲取標簽內部文本內容

1 # tag = soup.find('a')
2 # v = tag.get_text('id')
3 # print(v)

14. index,檢查標簽在某標簽中的索引位置

1 # tag = soup.find('body')
2 # v = tag.index(tag.find('div'))
3 # print(v)
4  
5 # tag = soup.find('body')
6 # for i,v in enumerate(tag):
7 # print(i,v)

15. is_empty_element,是否是空標簽(是否可以是空)或者自閉合標簽,

     判斷是否是如下標簽:'br' , 'hr', 'input', 'img', 'meta','spacer', 'link', 'frame', 'base'

1 # tag = soup.find('br')
2 # v = tag.is_empty_element
3 # print(v)

16. 當前的關聯標簽

 1 # soup.next
 2 # soup.next_element
 3 # soup.next_elements
 4 # soup.next_sibling
 5 # soup.next_siblings
 6  
 7 #
 8 # tag.previous
 9 # tag.previous_element
10 # tag.previous_elements
11 # tag.previous_sibling
12 # tag.previous_siblings
13  
14 #
15 # tag.parent
16 # tag.parents

17. 查找某標簽的關聯標簽

 1 # tag.find_next(...)
 2 # tag.find_all_next(...)
 3 # tag.find_next_sibling(...)
 4 # tag.find_next_siblings(...)
 5  
 6 # tag.find_previous(...)
 7 # tag.find_all_previous(...)
 8 # tag.find_previous_sibling(...)
 9 # tag.find_previous_siblings(...)
10  
11 # tag.find_parent(...)
12 # tag.find_parents(...)
13  
14 # 參數同find_all

18. select,select_one, CSS選擇器

 1 soup.select("title")
 2  
 3 soup.select("p nth-of-type(3)")
 4  
 5 soup.select("body a")
 6  
 7 soup.select("html head title")
 8  
 9 tag = soup.select("span,a")
10  
11 soup.select("head > title")
12  
13 soup.select("p > a")
14  
15 soup.select("p > a:nth-of-type(2)")
16  
17 soup.select("p > #link1")
18  
19 soup.select("body > a")
20  
21 soup.select("#link1 ~ .sister")
22  
23 soup.select("#link1 + .sister")
24  
25 soup.select(".sister")
26  
27 soup.select("[class~=sister]")
28  
29 soup.select("#link1")
30  
31 soup.select("a#link2")
32  
33 soup.select('a[href]')
34  
35 soup.select('a[href="http://example.com/elsie"]')
36  
37 soup.select('a[href^="http://example.com/"]')
38  
39 soup.select('a[href$="tillie"]')
40  
41 soup.select('a[href*=".com/el"]')
42  
43  
44 from bs4.element import Tag
45  
46 def default_candidate_generator(tag):
47     for child in tag.descendants:
48         if not isinstance(child, Tag):
49             continue
50         if not child.has_attr('href'):
51             continue
52         yield child
53  
54 tags = soup.find('body').select("a", _candidate_generator=default_candidate_generator)
55 print(type(tags), tags)
56  
57 from bs4.element import Tag
58 def default_candidate_generator(tag):
59     for child in tag.descendants:
60         if not isinstance(child, Tag):
61             continue
62         if not child.has_attr('href'):
63             continue
64         yield child
65  
66 tags = soup.find('body').select("a", _candidate_generator=default_candidate_generator, limit=1)
67 print(type(tags), tags)
View Code

19. 標簽的內容

 1 # tag = soup.find('span')
 2 # print(tag.string)          # 獲取
 3 # tag.string = 'new content' # 設置
 4 # print(soup)
 5  
 6 # tag = soup.find('body')
 7 # print(tag.string)
 8 # tag.string = 'xxx'
 9 # print(soup)
10  
11 # tag = soup.find('body')
12 # v = tag.stripped_strings  # 遞歸內部獲取所有標簽的文本
13 # print(v)

20.append在當前標簽內部追加一個標簽

 1 # tag = soup.find('body')
 2 # tag.append(soup.find('a'))
 3 # print(soup)
 4 #
 5 # from bs4.element import Tag
 6 # obj = Tag(name='i',attrs={'id': 'it'})
 7 # obj.string = '我是一個新來的'
 8 # tag = soup.find('body')
 9 # tag.append(obj)
10 # print(soup)

21.insert在當前標簽內部指定位置插入一個標簽

1 # from bs4.element import Tag
2 # obj = Tag(name='i', attrs={'id': 'it'})
3 # obj.string = '我是一個新來的'
4 # tag = soup.find('body')
5 # tag.insert(2, obj)
6 # print(soup)

22. insert_after,insert_before 在當前標簽后面或前面插入

1 # from bs4.element import Tag
2 # obj = Tag(name='i', attrs={'id': 'it'})
3 # obj.string = '我是一個新來的'
4 # tag = soup.find('body')
5 # # tag.insert_before(obj)
6 # tag.insert_after(obj)
7 # print(soup)

23. replace_with 在當前標簽替換為指定標簽

1 # from bs4.element import Tag
2 # obj = Tag(name='i', attrs={'id': 'it'})
3 # obj.string = '我是一個新來的'
4 # tag = soup.find('div')
5 # tag.replace_with(obj)
6 # print(soup)

24. 創建標簽之間的關系(但不會改變標簽的位置)

1 # tag = soup.find('div')
2 # a = soup.find('a')
3 # tag.setup(previous_sibling=a)
4 # print(tag.previous_sibling)

25. wrap,將指定標簽把當前標簽包裹起來

 1 # from bs4.element import Tag
 2 # obj1 = Tag(name='div', attrs={'id': 'it'})
 3 # obj1.string = '我是一個新來的'
 4 #
 5 # tag = soup.find('a')
 6 # v = tag.wrap(obj1)
 7 # print(soup)
 8  
 9 # tag = soup.find('a')
10 # v = tag.wrap(soup.find('p'))
11 # print(soup)

26. unwrap,去掉當前標簽,將保留其包裹的標簽

1 # tag = soup.find('a')
2 # v = tag.unwrap()
3 # print(soup)

 

轉載自:

http://www.cnblogs.com/wupeiqi/articles/6283017.html

 

更多參考:

Beautiful Soup 4.4.0 文檔


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