在python過濾器函數中使用re.search

Question

我無法在過濾器表達式中使用re.search。

我正在嘗試使用re.search從每個元素是html行的列表中提取href值。

這是我在做什么：

>>> filter(lambda html_line: re.search('.*a href=\"([^\"]*).*', html_line), data)

[u'Directory Feb 28 23:57 <b><a href="/MyApp/LogBrowser?type=crawler/2014.02.28">2014.02.28</a></b>'
 u'Directory Mar 01 23:59 <b><a href="/MyApp/LogBrowser?type=crawler/2014.03.01">2014.03.01</a></b>'
 u'Directory Mar 02 23:50 <b><a href="/MyApp/LogBrowser?type=crawler/2014.03.02">2014.03.02</a></b>'
 u'Directory Mar 03 23:59 <b><a href="/MyApp/LogBrowser?type=crawler/2014.03.03">2014.03.03</a></b>'
 u'Directory Mar 04 23:50 <b><a href="/MyApp/LogBrowser?type=crawler/2014.03.04">2014.03.04</a></b>'
 u'Directory Mar 05 23:50 <b><a href="/MyApp/LogBrowser?type=crawler/2014.03.05">2014.03.05</a></b>'
 u'Directory Mar 06 23:50 <b><a href="/MyApp/LogBrowser?type=crawler/2014.03.06">2014.03.06</a></b>'
 u'Directory Mar 07 23:50 <b><a href="/MyApp/LogBrowser?type=crawler/2014.03.07">2014.03.07</a></b>'
 u'Directory Mar 08 23:50 <b><a href="/MyApp/LogBrowser?type=crawler/2014.03.08">2014.03.08</a></b>']

我的研究電話似乎工作正常。

例如，這有效：

>>> for html_line in data:
    print re.search('.*a href=\"([^\"]*).*', html_line).group(1)

/MyApp/LogBrowser?type=crawler/2014.02.28
/MyApp/LogBrowser?type=crawler/2014.03.01
/MyApp/LogBrowser?type=crawler/2014.03.02
/MyApp/LogBrowser?type=crawler/2014.03.03
/MyApp/LogBrowser?type=crawler/2014.03.04
/MyApp/LogBrowser?type=crawler/2014.03.05
/MyApp/LogBrowser?type=crawler/2014.03.06
/MyApp/LogBrowser?type=crawler/2014.03.07
/MyApp/LogBrowser?type=crawler/2014.03.08

Answer 1

filter只會過濾不會返回href值的項目，您可以為此使用列表推導：

r = re.compile(r'.*a href=\"([^\"]*).*')
data = [x.group(1) for x in (r.search(html_line) for html_line in data)
                                                                if x is not None]