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。

我想使用re.search從列表中提取href值，其中每個元素都是html行。

下面是我在做什麼：

>>> 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re.search通話似乎正常工作。

例如，這個工程：

>>> 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只會過濾它不會返回href值的項目，你可以使用這個列表理解：

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]