从维基百科文章中获取第一段

Question

我正在使用以下代码来获取维基百科文章的第一段。这里是我代码的运行结果。我只需要这一段内容。这样做可以吗？或者有没有更好的方法？

'''Papori''' ({{lang-as|'''?????'''}}) 是一部由[[Jahnu Barua]]执导的[[阿萨姆语]]故事片。影片的主演有Gopi Desai、[[Biju Phukan]]、Sushil Goswami、Chetana Das和Dulal Roy。这部电影于1986年上映。

这是我的代码：

#!/usr/bin/python
from lxml import etree
import urllib
from BeautifulSoup import BeautifulSoup

class AppURLopener(urllib.FancyURLopener):
    version = "WikiDownloader"

urllib._urlopener = AppURLopener()
query = 'http://en.wikipedia.org/w/api.php?action=query&prop=revisions&rvprop=content&format=xml&titles=papori&rvsection=0'
#data = { 'catname':'', 'wpDownload':1, 'pages':"\n".join(pages)}
#data = urllib.urlencode(data)
f = urllib.urlopen(query)
s = f.read()
#doc = etree.parse(f)
#print(s)
soup = BeautifulSoup(s)
secondPTag = soup.findAll('rev')
print secondPTag

代码更新：有没有人能帮我去掉{{ }}之间的文字？因为这些内容不需要。谢谢！

Answer 1

是的，这是可能的。你可以使用一个叫做 HTMLParser 的工具来解析HTML，但我更推荐使用 Beautiful Soup。

你可以用正则表达式来去掉一些子字符串，像这样：

>>> email = "tony@tiremove_thisger.net"
>>> m = re.search("remove_this", email)
>>> email[:m.start()] + email[m.end():]
'tony@tiger.net'

Answer 2

要删除从 {{ 到 '''Papori''' 之间的所有内容：

import re
regex = re.compile(r"""{{.*?}}\s*('''Papori''')""", re.DOTALL)
print regex.sub(r"\1", rev_data)

要删除从第一个 "{{" 到匹配的 "}}" 之间的所有内容：

prefix, sep, rest = rev_data.partition("{{")
if sep: # found the first "{{"
    rest = sep + rest # put it back
    while rest.startswith("{{"):
        # remove nested "{{expr}}" one by one until there is none
        rest, n = re.subn(r"{{(?:[^{]|(?<!{){)*?}}", "", rest, 1)
        if n == 0: 
            break # the first "{{" is unmatched; can't remove it
    else: # deletion is successful
        rev_data = prefix + rest
print(rev_data)

要删除从第一个 "{{" 到匹配的 "}}" 之间的所有内容，但不使用正则表达式：

prefix, sep, rest = rev_data.partition("{{")
if sep: # found the first "{{"
    depth = 1
    prevc = None
    for i, c in enumerate(rest):
        if c == "{" and  prevc == c:  # found "{{"
            depth += 1
            prevc = None # match "{{{ " only once
        elif c == "}" and prevc == c: # found "}}"
            depth -= 1
            if depth == 0: # found matching "}}"
                rev_data = prefix + rest[i+1:] # after matching "}}"
                break
            prevc = None # match "}}} " only once
        else:
            prevc = c
print(rev_data)

完整示例

#!/usr/bin/env python
import urllib, urllib2
import xml.etree.cElementTree as etree

# download & parse xml, find rev data
params = dict(action="query", prop="revisions", rvprop="content",
              format="xml", titles="papori", rvsection=0)
request = urllib2.Request(
    "http://en.wikipedia.org/w/api.php?" + urllib.urlencode(params), 
    headers={"User-Agent": "WikiDownloader/1.0",
             "Referer": "http://stackoverflow.com/q/7937855"})
tree = etree.parse(urllib2.urlopen(request))
rev_data = tree.findtext('.//rev')

# remove everything from the first "{{" to matching "}}"
prefix, sep, rest = rev_data.partition("{{")
if sep: # found the first "{{"
    depth = 1
    prevc = None
    for i, c in enumerate(rest):
        if c == "{" and  prevc == c:  # found "{{"
            depth += 1
            prevc = None # match "{{{ " only once
        elif c == "}" and prevc == c: # found "}}"
            depth -= 1
            if depth == 0: # found matching "}}"
                rev_data = prefix + rest[i+1:] # after matching "}}"
                break
            prevc = None # match "}}} " only once
        else:
            prevc = c
print rev_data

输出结果

'''Papori''' ({{lang-as|'''পাপৰী'''}}) is an [[Assamese
language]] feature film directed by [[Jahnu Barua]]. The film
stars Gopi Desai, [[Biju Phukan]], Sushil Goswami, Chetana Das
and Dulal Roy. The film was released in 1986.<ref name="ab">{{cite
web|url=http://www.chaosmag.in/barua.html|title=Papori – 1986 –
Assamese film|publisher=Chaosmag|accessdate=4 February
2010}}</ref>