Python正则表达式超过字符串列表

Question

我正在尝试从字符串列表中提取 url。样品清单：

import re
p = ['<img class="alignnone size-full wp-image-2087" src="http://www.sample.com/test.jpg" alt="0wCR41v" width="540" height="720" srcset="http://www.sample.com/test-225x300.jpg 225w, http://www.sample.com/test.jpg 540w" sizes="(max-width: 540px) 100vw, 540px" />', '<img class="alignnone size-large wp-image-2133" src="http://www.sample.com/test2.jpg" alt="NtAboHF" width="583" height="1024" srcset="http://www.happyfridaygents.com/wp-content/uploads/2016/04/NtAboHF-768x1349.jpg 768w, http://www.sample.com/test2.jpg 583w, http://www.happyfridaygents.com/wp-content/uploads/2016/04/NtAboHF.jpg 828w" sizes="(max-width: 583px) 100vw, 583px" />']

我想提取紧跟在 src=" 部分之后的 http://www.sample.com/test.jpg 部分。

如果 p 只是一个这样的字符串，我可以使用 findall：

t = re.findall('src="(.+)" alt', p)
print t

但是如何遍历列表并返回 P 中所有 url 的列表？

Answer 1

这是使用BeautifulSoup的解决方案：

>>> p = ['<img class="alignnone size-full wp-image-2087" src="http://www.sample.com/test.jpg" alt="0wCR41v" width="540" height="720" srcset="http://www.sample.com/test-225x300.jpg 225w, http://www.sample.com/test.jpg 540w" sizes="(max-width: 540px) 100vw, 540px" />', '<img class="alignnone size-large wp-image-2133" src="http://www.sample.com/test2.jpg" alt="NtAboHF" width="583" height="1024" srcset="http://www.happyfridaygents.com/wp-content/uploads/2016/04/NtAboHF-768x1349.jpg 768w, http://www.sample.com/test2.jpg 583w, http://www.happyfridaygents.com/wp-content/uploads/2016/04/NtAboHF.jpg 828w" sizes="(max-width: 583px) 100vw, 583px" />']

>>> from bs4 import BeautifulSoup
>>> soup = BeautifulSoup(''.join(p), 'html.parser')
>>> src_links = [img['src'] for img in soup.find_all('img')]

>>> src_links
[u'http://www.sample.com/test.jpg', u'http://www.sample.com/test2.jpg']

如果你确实想使用正则表达式：

>>> regex = re.compile(r'src="(.+)" alt')
>>> [regex.search(img).group(1) for img in p]
['http://www.sample.com/test.jpg', 'http://www.sample.com/test2.jpg']

Answer 2

如何循环执行：

>>> pe = re.compile('src="(.+)" alt')
>>> for img in p:
...     print pe.findall(img)
... 
['http://www.sample.com/test.jpg']
['http://www.sample.com/test2.jpg']

Answer 3

这是你想要的吗？

import re
p = ['<img class="alignnone size-full wp-image-2087" src="http://www.sample.com/test.jpg" alt="0wCR41v" width="540" height="720" srcset="http://www.sample.com/test-225x300.jpg 225w, http://www.sample.com/test.jpg 540w" sizes="(max-width: 540px) 100vw, 540px" />', '<img class="alignnone size-large wp-image-2133" src="http://www.sample.com/test2.jpg" alt="NtAboHF" width="583" height="1024" srcset="http://www.happyfridaygents.com/wp-content/uploads/2016/04/NtAboHF-768x1349.jpg 768w, http://www.sample.com/test2.jpg 583w, http://www.happyfridaygents.com/wp-content/uploads/2016/04/NtAboHF.jpg 828w" sizes="(max-width: 583px) 100vw, 583px" />']
outList = [re.findall('src="(.+)" alt', pp)[0] for pp in p]

Answer 4

使用列表推导：

l = [re.findall('src="(.+)" alt', each_url) for each_url in p] 

这将为您提供可以链接在一起的列表：

import itertools
urls = list(itertools.chain(*l))

不过，其他地方给出的正则表达式答案更优雅。

Answer 5

for i in p:
    t = re.findall('src="(.+)" alt', i)
    print t

更新：

k=[re.findall('src="(.+)" alt',i) for i in p]
[item for sublist in k for item in sublist]

['http://www.sample.com/test.jpg', 'http://www.sample.com/test2.jpg']