• BeautifulSoup在HTML或XML中查找指定元素变得简单


    BeautifulSoup

    BeautifulSoup是一个模块,该模块用于接收一个HTML或XML字符串,然后将其进行格式化,之后遍可以使用他提供的方法进行快速查找指定元素,从而使得在HTML或XML中查找指定元素变得简单。

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    from bs4 import BeautifulSoup
     
    html_doc = """
    <html><head><title>The Dormouse's story</title></head>
    <body>
    asdf
        <div class="title">
            <b>The Dormouse's story总共</b>
            <h1>f</h1>
        </div>
    <div class="story">Once upon a time there were three little sisters; and their names were
        <a  class="sister0" id="link1">Els<span>f</span>ie</a>,
        <a href="http://example.com/lacie" class="sister" id="link2">Lacie</a> and
        <a href="http://example.com/tillie" class="sister" id="link3">Tillie</a>;
    and they lived at the bottom of a well.</div>
    ad<br/>sf
    <p class="story">...</p>
    </body>
    </html>
    """
     
    soup = BeautifulSoup(html_doc, features="lxml")
    # 找到第一个a标签
    tag1 = soup.find(name='a')
    # 找到所有的a标签
    tag2 = soup.find_all(name='a')
    # 找到id=link2的标签
    tag3 = soup.select('#link2')

    安装:

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    pip3 install beautifulsoup4

    使用示例:

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    from bs4 import BeautifulSoup
     
    html_doc = """
    <html><head><title>The Dormouse's story</title></head>
    <body>
        ...
    </body>
    </html>
    """
     
    soup = BeautifulSoup(html_doc, features="lxml")

    1. name,标签名称

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    # tag = soup.find('a')
    # name = tag.name # 获取
    # print(name)
    # tag.name = 'span' # 设置
    # print(soup)

    2. attr,标签属性

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    # tag = soup.find('a')
    # attrs = tag.attrs    # 获取
    # print(attrs)
    # tag.attrs = {'ik':123} # 设置
    # tag.attrs['id'] = 'iiiii' # 设置
    # print(soup)

    3. children,所有子标签

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

    4. children,所有子子孙孙标签

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

    5. clear,将标签的所有子标签全部清空(保留标签名)

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

    6. decompose,递归的删除所有的标签

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    # body = soup.find('body')
    # body.decompose()
    # print(soup)

    7. extract,递归的删除所有的标签,并获取删除的标签

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

    8. decode,转换为字符串(含当前标签);decode_contents(不含当前标签)

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    # body = soup.find('body')
    # v = body.decode()
    # v = body.decode_contents()
    # print(v)

    9. encode,转换为字节(含当前标签);encode_contents(不含当前标签)

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    # body = soup.find('body')
    # v = body.encode()
    # v = body.encode_contents()
    # print(v)

    10. find,获取匹配的第一个标签

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

    11. find_all,获取匹配的所有标签

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    # tags = soup.find_all('a')
    # print(tags)
     
    # tags = soup.find_all('a',limit=1)
    # print(tags)
     
    # tags = soup.find_all(name='a', attrs={'class': 'sister'}, recursive=True, text='Lacie')
    # # tags = soup.find(name='a', class_='sister', recursive=True, text='Lacie')
    # print(tags)
     
     
    # ####### 列表 #######
    # v = soup.find_all(name=['a','div'])
    # print(v)
     
    # v = soup.find_all(class_=['sister0', 'sister'])
    # print(v)
     
    # v = soup.find_all(text=['Tillie'])
    # print(v, type(v[0]))
     
     
    # v = soup.find_all(id=['link1','link2'])
    # print(v)
     
    # v = soup.find_all(href=['link1','link2'])
    # print(v)
     
    # ####### 正则 #######
    import re
    # rep = re.compile('p')
    # rep = re.compile('^p')
    # v = soup.find_all(name=rep)
    # print(v)
     
    # rep = re.compile('sister.*')
    # v = soup.find_all(class_=rep)
    # print(v)
     
    # rep = re.compile('http://www.oldboy.com/static/.*')
    # v = soup.find_all(href=rep)
    # print(v)
     
    # ####### 方法筛选 #######
    # def func(tag):
    # return tag.has_attr('class') and tag.has_attr('id')
    # v = soup.find_all(name=func)
    # print(v)
     
     
    # ## get,获取标签属性
    # tag = soup.find('a')
    # v = tag.get('id')
    # print(v)

    12. has_attr,检查标签是否具有该属性

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

    13. get_text,获取标签内部文本内容

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

    14. index,检查标签在某标签中的索引位置

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    # tag = soup.find('body')
    # v = tag.index(tag.find('div'))
    # print(v)
     
    # tag = soup.find('body')
    # for i,v in enumerate(tag):
    # print(i,v)

    15. is_empty_element,是否是空标签(是否可以是空)或者自闭合标签,

         判断是否是如下标签:'br' , 'hr', 'input', 'img', 'meta','spacer', 'link', 'frame', 'base'

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

    16. 当前的关联标签

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    # soup.next
    # soup.next_element
    # soup.next_elements
    # soup.next_sibling
    # soup.next_siblings
     
    #
    # tag.previous
    # tag.previous_element
    # tag.previous_elements
    # tag.previous_sibling
    # tag.previous_siblings
     
    #
    # tag.parent
    # tag.parents

    17. 查找某标签的关联标签

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    # tag.find_next(...)
    # tag.find_all_next(...)
    # tag.find_next_sibling(...)
    # tag.find_next_siblings(...)
     
    # tag.find_previous(...)
    # tag.find_all_previous(...)
    # tag.find_previous_sibling(...)
    # tag.find_previous_siblings(...)
     
    # tag.find_parent(...)
    # tag.find_parents(...)
     
    # 参数同find_all

    18. select,select_one, CSS选择器

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    soup.select("title")
     
    soup.select("p nth-of-type(3)")
     
    soup.select("body a")
     
    soup.select("html head title")
     
    tag = soup.select("span,a")
     
    soup.select("head > title")
     
    soup.select("p > a")
     
    soup.select("p > a:nth-of-type(2)")
     
    soup.select("p > #link1")
     
    soup.select("body > a")
     
    soup.select("#link1 ~ .sister")
     
    soup.select("#link1 + .sister")
     
    soup.select(".sister")
     
    soup.select("[class~=sister]")
     
    soup.select("#link1")
     
    soup.select("a#link2")
     
    soup.select('a[href]')
     
    soup.select('a[href="http://example.com/elsie"]')
     
    soup.select('a[href^="http://example.com/"]')
     
    soup.select('a[href$="tillie"]')
     
    soup.select('a[href*=".com/el"]')
     
     
    from bs4.element import Tag
     
    def default_candidate_generator(tag):
        for child in tag.descendants:
            if not isinstance(child, Tag):
                continue
            if not child.has_attr('href'):
                continue
            yield child
     
    tags = soup.find('body').select("a", _candidate_generator=default_candidate_generator)
    print(type(tags), tags)
     
    from bs4.element import Tag
    def default_candidate_generator(tag):
        for child in tag.descendants:
            if not isinstance(child, Tag):
                continue
            if not child.has_attr('href'):
                continue
            yield child
     
    tags = soup.find('body').select("a", _candidate_generator=default_candidate_generator, limit=1)
    print(type(tags), tags)

    19. 标签的内容

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    # tag = soup.find('span')
    # print(tag.string)          # 获取
    # tag.string = 'new content' # 设置
    # print(soup)
     
    # tag = soup.find('body')
    # print(tag.string)
    # tag.string = 'xxx'
    # print(soup)
     
    # tag = soup.find('body')
    # v = tag.stripped_strings  # 递归内部获取所有标签的文本
    # print(v)

    20.append在当前标签内部追加一个标签

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    # tag = soup.find('body')
    # tag.append(soup.find('a'))
    # print(soup)
    #
    # from bs4.element import Tag
    # obj = Tag(name='i',attrs={'id': 'it'})
    # obj.string = '我是一个新来的'
    # tag = soup.find('body')
    # tag.append(obj)
    # print(soup)

    21.insert在当前标签内部指定位置插入一个标签

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    # from bs4.element import Tag
    # obj = Tag(name='i', attrs={'id': 'it'})
    # obj.string = '我是一个新来的'
    # tag = soup.find('body')
    # tag.insert(2, obj)
    # print(soup)

    22. insert_after,insert_before 在当前标签后面或前面插入

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    # from bs4.element import Tag
    # obj = Tag(name='i', attrs={'id': 'it'})
    # obj.string = '我是一个新来的'
    # tag = soup.find('body')
    # # tag.insert_before(obj)
    # tag.insert_after(obj)
    # print(soup)

    23. replace_with 在当前标签替换为指定标签

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    # from bs4.element import Tag
    # obj = Tag(name='i', attrs={'id': 'it'})
    # obj.string = '我是一个新来的'
    # tag = soup.find('div')
    # tag.replace_with(obj)
    # print(soup)

    24. 创建标签之间的关系

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    # tag = soup.find('div')
    # a = soup.find('a')
    # tag.setup(previous_sibling=a)
    # print(tag.previous_sibling)

    25. wrap,将指定标签把当前标签包裹起来

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    # from bs4.element import Tag
    # obj1 = Tag(name='div', attrs={'id': 'it'})
    # obj1.string = '我是一个新来的'
    #
    # tag = soup.find('a')
    # v = tag.wrap(obj1)
    # print(soup)
     
    # tag = soup.find('a')
    # v = tag.wrap(soup.find('p'))
    # print(soup)

    26. unwrap,去掉当前标签,将保留其包裹的标签

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

    更多参数官方:http://beautifulsoup.readthedocs.io/zh_CN/v4.4.0/

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  • 原文地址:https://www.cnblogs.com/xyhh/p/11187206.html
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