所以我对这个理论很感兴趣，如果你去一个随机的维基百科文章，重复点击不在括号内的第一个链接，在 95% 的情况下，你最终会看到关于哲学的文章。
我想用 Python 编写一个脚本，为我获取链接，最后打印一个很好的列表，列出访问过的文章（linkA -> linkB -> linkC）等。
我设法获得了网页的 HTML DOM，并设法去掉了一些不必要的链接和导致消歧页面的顶部描述栏。到目前为止，我得出的结论是：
- DOM 以您在某些页面右侧看到的表格开始，例如Human中。我们想忽略这些链接。
- 有效的链接元素都有一个
<p>元素作为它们的祖先（通常是父或祖父，如果它在一个<b>。通向消歧页面的顶部栏似乎不包含任何<p>元素。 - 无效链接包含一些特殊的单词，后跟一个冒号，例如
Wikipedia:
到目前为止，一切都很好。但正是括号吸引了我。在文章中关于人类的文章中，不在括号内的第一个链接是“/wiki/Species”，但脚本会在其中找到“/wiki/Taxonomy”。
我不知道如何以编程方式进行此操作，因为我必须在父/子节点的某种组合中查找可能并不总是相同的文本。有任何想法吗？
我的代码可以在下面看到，但这是我很快就编出来的东西，而且我并不十分自豪。然而，它被评论了，所以你可以看到我的想法（我希望:)）。
"""Wikipedia fun"""
import urllib2
from xml.dom.minidom import parseString
import time
def validWikiArticleLinkString(href):
""" Takes a string and returns True if it contains the substring
'/wiki/' in the beginning and does not contain any of the
"special" wiki pages.
"""
return (href.find("/wiki/") == 0
and href.find("(disambiguation)") == -1
and href.find("File:") == -1
and href.find("Wikipedia:") == -1
and href.find("Portal:") == -1
and href.find("Special:") == -1
and href.find("Help:") == -1
and href.find("Template_talk:") == -1
and href.find("Template:") == -1
and href.find("Talk:") == -1
and href.find("Category:") == -1
and href.find("Bibcode") == -1
and href.find("Main_Page") == -1)
if __name__ == "__main__":
visited = [] # a list of visited links. used to avoid getting into loops
opener = urllib2.build_opener()
opener.addheaders = [('User-agent', 'Mozilla/5.0')] # need headers for the api
currentPage = "Human" # the page to start with
while True:
infile = opener.open('http://en.wikipedia.org/w/index.php?title=%s&printable=yes' % currentPage)
html = infile.read() # retrieve the contents of the wiki page we are at
htmlDOM = parseString(html) # get the DOM of the parsed HTML
aTags = htmlDOM.getElementsByTagName("a") # find all <a> tags
for tag in aTags:
if "href" in tag.attributes.keys(): # see if we have the href attribute in the tag
href = tag.attributes["href"].value # get the value of the href attribute
if validWikiArticleLinkString(href): # if we have one of the link types we are looking for
# Now come the tricky parts. We want to look for links in the main content area only,
# and we want the first link not in parentheses.
# assume the link is valid.
invalid = False
# tables which appear to the right on the site appear first in the DOM, so we need to make sure
# we are not looking at a <a> tag somewhere inside a <table>.
pn = tag.parentNode
while pn is not None:
if str(pn).find("table at") >= 0:
invalid = True
break
else:
pn = pn.parentNode
if invalid: # go to next link
continue
# Next we look at the descriptive texts above the article, if any; e.g
# This article is about .... or For other uses, see ... (disambiguation).
# These kinds of links will lead into loops so we classify them as invalid.
# We notice that this text does not appear to be inside a <p> block, so
# we dismiss <a> tags which aren't inside any <p>.
pnode = tag.parentNode
while pnode is not None:
if str(pnode).find("p at") >= 0:
break
pnode = pnode.parentNode
# If we have reached the root node, which has parentNode None, we classify the
# link as invalid.
if pnode is None:
invalid = True
if invalid:
continue
###### this is where I got stuck:
# now we need to look if the link is inside parentheses. below is some junk
# for elem in tag.parentNode.childNodes:
# while elem.firstChild is not None:
# elem = elem.firstChid
# print elem.nodeValue
print href # this will be the next link
newLink = href[6:] # except for the /wiki/ part
break
# if we have been to this link before, break the loop
if newLink in visited:
print "Stuck in loop."
break
# or if we have reached Philosophy
elif newLink == "Philosophy":
print "Ended up in Philosophy."
break
else:
visited.append(currentPage) # mark this currentPage as visited
currentPage = newLink # make the the currentPage we found the new page to fetch
time.sleep(5) # sleep some to see results as debug