如何使用python从网站中提取带有匹配词的html链接

Question

我有一个网址，比如http://www.bbc.com/news/world/asia/。就在这个页面中，我想提取所有包含 India 或 INDIA 或 india 的链接（应该不区分大小写）。

如果我点击任何输出链接，它应该会将我带到相应的页面，例如，这些是几行让印度印度对 Dhoni 退休感到震惊和 印度雾继续造成混乱。如果我点击这些链接，我应该分别被重定向到 http://www.bbc.com/news/world-asia-india-30640436 和 http://www.bbc.com/news/world-asia-india-30630274。

import urllib
from bs4 import BeautifulSoup
import re
import requests
url = "http://www.bbc.com/news/world/asia/"
r = requests.get(url)
data = r.text
soup = BeautifulSoup(data)
only_links = SoupStrainer('a', href=re.compile('india'))
print (only_links)

我在 python 3.4.2 中编写了非常基本的最小代码。

Answer 1

您需要在显示的文本中搜索单词india。为此，您需要一个自定义函数：

from bs4 import BeautifulSoup
import requests

url = "http://www.bbc.com/news/world/asia/"
r = requests.get(url)
soup = BeautifulSoup(r.content)

india_links = lambda tag: (getattr(tag, 'name', None) == 'a' and
                           'href' in tag.attrs and
                           'india' in tag.get_text().lower())
results = soup.find_all(india_links)

india_links lambda 会查找所有标记为 <a> 的标记，链接具有 href 属性并在显示的文本中某处包含 india（不区分大小写）。

注意我使用了requests响应对象.content属性；将解码交给 BeautifulSoup！

演示：

>>> from bs4 import BeautifulSoup
>>> import requests
>>> url = "http://www.bbc.com/news/world/asia/"
>>> r = requests.get(url)
>>> soup = BeautifulSoup(r.content)
>>> india_links = lambda tag: getattr(tag, 'name', None) == 'a' and 'href' in tag.attrs and 'india' in tag.get_text().lower()
>>> results = soup.find_all(india_links)
>>> from pprint import pprint
>>> pprint(results)
[<a href="/news/world/asia/india/">India</a>,
 <a class="story" href="/news/world-asia-india-30647504" rel="published-1420102077277">India scheme to monitor toilet use </a>,
 <a class="story" href="/news/world-asia-india-30640444" rel="published-1420022868334">India to scrap tax breaks on cars</a>,
 <a class="story" href="/news/world-asia-india-30640436" rel="published-1420012598505">India shock over Dhoni retirement</a>,
 <a href="/news/world/asia/india/">India</a>,
 <a class="headline-anchor" href="/news/world-asia-india-30630274" rel="published-1419931669523"><img alt="A Delhi police officer with red flag walks amidst morning fog in Delhi, India, Monday, Dec 29, 2014. " src="http://news.bbcimg.co.uk/media/images/79979000/jpg/_79979280_79979240.jpg"/><span class="headline heading-13">India fog continues to cause chaos</span></a>,
 <a class="headline-anchor" href="/news/world-asia-india-30632852" rel="published-1419940599384"><span class="headline heading-13">Court boost to India BJP chief</span></a>,
 <a class="headline-anchor" href="/sport/0/cricket/30632182" rel="published-1419930930045"><span class="headline heading-13">India captain Dhoni quits Tests</span></a>,
 <a class="story" href="http://www.bbc.co.uk/news/world-radio-and-tv-15386555" rel="published-1392018507550"><img alt="A woman riding a scooter waits for a traffic signal along a street in Mumbai February 5, 2014." src="http://news.bbcimg.co.uk/media/images/72866000/jpg/_72866856_020889093.jpg"/>Special report: India Direct</a>,
 <a href="/2/hi/south_asia/country_profiles/1154019.stm">India</a>]

请注意此处的http://www.bbc.co.uk/news/world-radio-and-tv-15386555 链接；我们必须使用lambda 搜索，因为使用text 正则表达式的搜索不会找到该元素；包含的文本（Special report: India Direct）不是标签中的唯一元素，因此不会被找到。

/news/world-asia-india-30632852 链接也存在类似问题；嵌套的 <span> 元素使得 Court boost to India BJP Chief 标题文本不是链接标签的直接子元素。

你可以提取只是链接：

from urllib.parse import urljoin

result_links = [urljoin(url, tag['href']) for tag in results]

所有相对 URL 都相对于原始 URL 进行解析：

>>> from urllib.parse import urljoin
>>> result_links = [urljoin(url, tag['href']) for tag in results]
>>> pprint(result_links)
['http://www.bbc.com/news/world/asia/india/',
 'http://www.bbc.com/news/world-asia-india-30647504',
 'http://www.bbc.com/news/world-asia-india-30640444',
 'http://www.bbc.com/news/world-asia-india-30640436',
 'http://www.bbc.com/news/world/asia/india/',
 'http://www.bbc.com/news/world-asia-india-30630274',
 'http://www.bbc.com/news/world-asia-india-30632852',
 'http://www.bbc.com/sport/0/cricket/30632182',
 'http://www.bbc.co.uk/news/world-radio-and-tv-15386555',
 'http://www.bbc.com/2/hi/south_asia/country_profiles/1154019.stm']