Finish crawl web
learned from udacity
提示：在某些时候，你必须在page上调用get_page。这似乎违反直觉，但是我们用 page 这个词时，指的网页的网址 (url) 和文本内容 (html)。get_page所做的是，传入网页的网址 (url) 并返回文本内容 (html)。
采用Depth First Search 深度优先搜索
tip :
在某些时候，你必须在page上调用get_page。这似乎违反直觉，但是我们用 page 这个词时，
指的网页的网址 (url) 和文本内容 (html)。get_page所做的是，传入网页的网址 (url) 并返回文本内容 (html)。
def get_page(url):
# This is a simulated get_page procedure so that you can test your
# code on two pages "http://xkcd.com/353" and "http://xkcd.com/554".
# A procedure which actually grabs a page from the web will be
# introduced in unit 4.
try:
if url == "http://xkcd.com/353":
return '<?xml version="1.0" encoding="utf-8" ?><?xml-stylesheet href="http://imgs.xkcd.com/s/c40a9f8.css" type="text/css" media="screen" ?><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"><html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>xkcd: Python</title> <link rel="stylesheet" type="text/css" href="http://imgs.xkcd.com/s/c40a9f8.css" media="screen" title="Default" /> <!--[if IE]><link rel="stylesheet" type="text/css" href="http://imgs.xkcd.com/s/ecbbecc.css" media="screen" title="Default" /><![endif]--> <link rel="alternate" type="application/atom+xml" title="Atom 1.0" href="/atom.xml" /> <link rel="alternate" type="application/rss+xml" title="RSS 2.0" href="/rss.xml" /> <link rel="icon" href="http://imgs.xkcd.com/s/919f273.ico" type="image/x-icon" /> <link rel="shortcut icon" href="http://imgs.xkcd.com/s/919f273.ico" type="image/x-icon" /> </head> <body> <div id="container"> <div id="topContainer"> <div id="topLeft" class="dialog"> <div class="hd"><div class="c"></div></div> <div class="bd"> <div class="c"> <div class="s"> <ul> <li><a href="http://xkcd.com/554"">Archive</a><br /></li> <li><a href="http://blag.xkcd.com/">News/Blag</a><br /></li> <li><a href="http://store.xkcd.com/">Store</a><br /></li> <li><a href="/about/">About</a><br /></li> <li><a href="http://forums.xkcd.com/">Forums</a><br /></li> </ul> </div> </div> </div> <div class="ft"><div class="c"></div></div> </div> <div id="topRight" class="dialog"> <div class="hd"><div class="c"></div></div> <div class="bd"> <div class="c"> <div class="s"> <div id="topRightContainer"> <div id="logo"> <a href="/"><img src="http://imgs.xkcd.com/s/9be30a7.png" alt="xkcd.com logo" height="83" width="185"/></a> <h2><br />A webcomic of romance,<br/> sarcasm, math, and language.</h2> <div class="clearleft"></div> <br />XKCD updates every Monday, Wednesday, and Friday. </div> </div> </div> </div> </div> <div class="ft"><div class="c"></div></div> </div> </div> <div id="contentContainer"> <div id="middleContent" class="dialog"> <div class="hd"><div class="c"></div></div> <div class="bd"> <div class="c"> <div class="s"><h1>Python</h1><br/><br /><div class="menuCont"> <ul> <li><a href="/1/">|<</a></li> <li><a href="/352/" accesskey="p">< Prev</a></li> <li><a href="http://dynamic.xkcd.com/random/comic/" id="rnd_btn_t">Random</a></li> <li><a href="/354/" accesskey="n">Next ></a></li> <li><a href="/">>|</a></li> </ul></div><br/><br/><img src="http://imgs.xkcd.com/comics/python.png" title="I wrote 20 short programs in Python yesterday. It was wonderful. Perl, Im leaving you." alt="Python" /><br/><br/><div class="menuCont"> <ul> <li><a href="/1/">|<</a></li> <li><a href="/352/" accesskey="p">< Prev</a></li> <li><a href="http://dynamic.xkcd.com/random/comic/" id="rnd_btn_b">Random</a></li> <li><a href="/354/" accesskey="n">Next ></a></li> <li><a href="/">>|</a></li> </ul></div><h3>Permanent link to this comic: http://xkcd.com/353/</h3><h3>Image URL (for hotlinking/embedding): http://imgs.xkcd.com/comics/python.png</h3><div id="transcript" style="display: none">[[ Guy 1 is talking to Guy 2, who is floating in the sky ]]Guy 1: You39;re flying! How?Guy 2: Python!Guy 2: I learned it last night! Everything is so simple!Guy 2: Hello world is just 39;print "Hello, World!" 39;Guy 1: I dunno... Dynamic typing? Whitespace?Guy 2: Come join us! Programming is fun again! It39;s a whole new world up here!Guy 1: But how are you flying?Guy 2: I just typed 39;import antigravity39;Guy 1: That39;s it?Guy 2: ...I also sampled everything in the medicine cabinet for comparison.Guy 2: But i think this is the python.{{ I wrote 20 short programs in Python yesterday. It was wonderful. Perl, I39;m leaving you. }}</div> </div> </div> </div> <div class="ft"><div class="c"></div></div> </div> <div id="middleFooter" class="dialog"> <div class="hd"><div class="c"></div></div> <div class="bd"> <div class="c"> <div class="s"> <img src="http://imgs.xkcd.com/s/a899e84.jpg" width="520" height="100" alt="Selected Comics" usemap=" comicmap" /> <map name="comicmap"> <area shape="rect" coords="0,0,100,100" href="/150/" alt="Grownups" /> <area shape="rect" coords="104,0,204,100" href="/730/" alt="Circuit Diagram" /> <area shape="rect" coords="208,0,308,100" href="/162/" alt="Angular Momentum" /> <area shape="rect" coords="312,0,412,100" href="/688/" alt="Self-Description" /> <area shape="rect" coords="416,0,520,100" href="/556/" alt="Alternative Energy Revolution" /> </map><br/><br />Search comic titles and transcripts:<br /><script type="text/javascript" src="//www.google.com/jsapi"></script><script type="text/javascript"> google.load("search", "1"); google.setOnLoadCallback(function() { google.search.CustomSearchControl.attachAutoCompletion( "012652707207066138651:zudjtuwe28q", document.getElementById("q"), "cse-search-box"); });</script><form action="//www.google.com/cse" id="cse-search-box"> <div> <input type="hidden" name="cx" value="012652707207066138651:zudjtuwe28q" /> <input type="hidden" name="ie" value="UTF-8" /> <input type="text" name="q" id="q" autocomplete="off" size="31" /> <input type="submit" name="sa" value="Search" /> </div></form><script type="text/javascript" src="//www.google.com/cse/brand?form=cse-search-box&lang=en"></script><a href="/rss.xml">RSS Feed</a> - <a href="/atom.xml">Atom Feed</a><br /> <br/> <div id="comicLinks"> Comics I enjoy:<br/> <a href="http://www.qwantz.com">Dinosaur Comics</a>, <a href="http://www.asofterworld.com">A Softer World</a>, <a href="http://pbfcomics.com/">Perry Bible Fellowship</a>, <a href="http://www.boltcity.com/copper/">Copper</a>, <a href="http://questionablecontent.net/">Questionable Content</a>, <a href="http://achewood.com/">Achewood</a>, <a href="http://wondermark.com/">Wondermark</a>, <a href="http://thisisindexed.com/">Indexed</a>, <a href="http://www.buttercupfestival.com/buttercupfestival.htm">Buttercup Festival</a> </div> <br/> Warning: this comic occasionally contains strong language (which may be unsuitable for children), unusual humor (which may be unsuitable for adults), and advanced mathematics (which may be unsuitable for liberal-arts majors).<br/> <br/> <h4>We did not invent the algorithm. The algorithm consistently finds Jesus. The algorithm killed Jeeves. <br />The algorithm is banned in China. The algorithm is from Jersey. The algorithm constantly finds Jesus.<br />This is not the algorithm. This is close.</h4><br/> <div class="line"></div> <br/> <div id="licenseText"> <!-- <a rel="license" href="http://creativecommons.org/licenses/by-nc/2.5/"><img alt="Creative Commons License" style="border:none" src="http://imgs.xkcd.com/static/somerights20.png" /></a><br/> --> This work is licensed under a <a rel="license" href="http://creativecommons.org/licenses/by-nc/2.5/">Creative Commons Attribution-NonCommercial 2.5 License</a>.<!-- <rdf:RDF xmlns="http://web.resource.org/cc/" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:dcterms="http://purl.org/dc/terms/" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns "><Work rdf:about=""><dc:creator>Randall Munroe</dc:creator><dcterms:rightsHolder>Randall Munroe</dcterms:rightsHolder><dc:type rdf:resource="http://purl.org/dc/dcmitype/StillImage" /><dc:source rdf:resource="http://www.xkcd.com/"/><license rdf:resource="http://creativecommons.org/licenses/by-nc/2.5/" /></Work><License rdf:about="http://creativecommons.org/licenses/by-nc/2.5/"><permits rdf:resource="http://web.resource.org/cc/Reproduction" /><permits rdf:resource="http://web.resource.org/cc/Distribution" /><requires rdf:resource="http://web.resource.org/cc/Notice" /><requires rdf:resource="http://web.resource.org/cc/Attribution" /><prohibits rdf:resource="http://web.resource.org/cc/CommercialUse" /><permits rdf:resource="http://web.resource.org/cc/DerivativeWorks" /></License></rdf:RDF> --> <br/> This means you"re free to copy and share these comics (but not to sell them). <a href="/license.html">More details</a>.<br/> </div> </div> </div> </div> <div class="ft"><div class="c"></div></div> </div> </div> </div> </body></html> '
elif url == "http://xkcd.com/554":
return '<?xml version="1.0" encoding="utf-8" ?> <?xml-stylesheet href="http://imgs.xkcd.com/s/c40a9f8.css" type="text/css" media="screen" ?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>xkcd: Not Enough Work</title> <link rel="stylesheet" type="text/css" href="http://imgs.xkcd.com/s/c40a9f8.css" media="screen" title="Default" /> <!--[if IE]><link rel="stylesheet" type="text/css" href="http://imgs.xkcd.com/s/ecbbecc.css" media="screen" title="Default" /><![endif]--> <link rel="alternate" type="application/atom+xml" title="Atom 1.0" href="/atom.xml" /> <link rel="alternate" type="application/rss+xml" title="RSS 2.0" href="/rss.xml" /> <link rel="icon" href="http://imgs.xkcd.com/s/919f273.ico" type="image/x-icon" /> <link rel="shortcut icon" href="http://imgs.xkcd.com/s/919f273.ico" type="image/x-icon" /> </head> <body> <div id="container"> <div id="topContainer"> <div id="topLeft" class="dialog"> <div class="hd"><div class="c"></div></div> <div class="bd"> <div class="c"> <div class="s"> <ul> <li><a href="/archive/">Archive</a><br /></li> <li><a href="http://blag.xkcd.com/">News/Blag</a><br /></li> <li><a href="http://store.xkcd.com/">Store</a><br /></li> <li><a href="/about/">About</a><br /></li> <li><a href="http://forums.xkcd.com/">Forums</a><br /></li> </ul> </div> </div> </div> <div class="ft"><div class="c"></div></div> </div> <div id="topRight" class="dialog"> <div class="hd"><div class="c"></div></div> <div class="bd"> <div class="c"> <div class="s"> <div id="topRightContainer"> <div id="logo"> <a href="/"><img src="http://imgs.xkcd.com/s/9be30a7.png" alt="xkcd.com logo" height="83" width="185"/></a> <h2><br />A webcomic of romance,<br/> sarcasm, math, and language.</h2> <div class="clearleft"></div> XKCD updates every Monday, Wednesday, and Friday. <br /> Blag: Remember geohashing? <a href="http://blog.xkcd.com/2012/02/27/geohashing-2/">Something pretty cool</a> happened Sunday. </div> </div> </div> </div> </div> <div class="ft"><div class="c"></div></div> </div> </div> <div id="contentContainer"> <div id="middleContent" class="dialog"> <div class="hd"><div class="c"></div></div> <div class="bd"> <div class="c"> <div class="s"> <h1>Not Enough Work</h1><br/> <br /> <div class="menuCont"> <ul> <li><a href="/1/">|<</a></li> <li><a href="/553/" accesskey="p">< Prev</a></li> <li><a href="http://dynamic.xkcd.com/random/comic/" id="rnd_btn_t">Random</a></li> <li><a href="/555/" accesskey="n">Next ></a></li> <li><a href="/">>|</a></li> </ul> </div> <br/> <br/> <img src="http://imgs.xkcd.com/comics/not_enough_work.png" title="It39;s even harder if you39;re an asshole who pronounces <> brackets." alt="Not Enough Work" /><br/> <br/> <div class="menuCont"> <ul> <li><a href="/1/">|<</a></li> <li><a href="/553/" accesskey="p">< Prev</a></li> <li><a href="http://dynamic.xkcd.com/random/comic/" id="rnd_btn_b">Random</a></li> <li><a href="/555/" accesskey="n">Next ></a></li> <li><a href="/">>|</a></li> </ul> </div> <h3>Permanent link to this comic: http://xkcd.com/554/</h3> <h3>Image URL (for hotlinking/embedding): http://imgs.xkcd.com/comics/not_enough_work.png</h3> <div id="transcript" style="display: none">Narration: Signs your coders don39;t have enough work to do: [[A man sitting at his workstation; a female co-worker behind him]] Man: I39;m almost up to my old typing speed in dvorak [[Two men standing by a server rack]] Man 1: Our servers now support gopher. Man 1: Just in case. [[A woman standing near her workstation speaking to a male co-worker]] Woman: Our pages are now HTML, XHTML-STRICT, and haiku-compliant Man: Haiku? Woman: <div class="main"> Woman: <span id="marquee"> Woman: Blog!< span>< div> [[A woman sitting at her workstation]] Woman: Hey! Have you guys seen this webcomic? {{title text: It39;s even harder if you39;re an asshole who pronounces <> brackets.}}</div> </div> </div> </div> <div class="ft"><div class="c"></div></div> </div> <div id="middleFooter" class="dialog"> <div class="hd"><div class="c"></div></div> <div class="bd"> <div class="c"> <div class="s"> <img src="http://imgs.xkcd.com/s/a899e84.jpg" width="520" height="100" alt="Selected Comics" usemap=" comicmap" /> <map name="comicmap"> <area shape="rect" coords="0,0,100,100" href="/150/" alt="Grownups" /> <area shape="rect" coords="104,0,204,100" href="/730/" alt="Circuit Diagram" /> <area shape="rect" coords="208,0,308,100" href="/162/" alt="Angular Momentum" /> <area shape="rect" coords="312,0,412,100" href="/688/" alt="Self-Description" /> <area shape="rect" coords="416,0,520,100" href="/556/" alt="Alternative Energy Revolution" /> </map><br/><br /> Search comic titles and transcripts:<br /> <script type="text/javascript" src="//www.google.com/jsapi"></script> <script type="text/javascript"> google.load("search", "1"); google.search.CustomSearchControl.attachAutoCompletion( "012652707207066138651:zudjtuwe28q", document.getElementById("q"), "cse-search-box"); }); </script> <form action="//www.google.com/cse" id="cse-search-box"> <div> <input type="hidden" name="cx" value="012652707207066138651:zudjtuwe28q" /> <input type="hidden" name="ie" value="UTF-8" /> <input type="text" name="q" id="q" autocomplete="off" size="31" /> <input type="submit" name="sa" value="Search" /> </div> </form> <script type="text/javascript" src="//www.google.com/cse/brand?form=cse-search-box&lang=en"></script> <a href="/rss.xml">RSS Feed</a> - <a href="/atom.xml">Atom Feed</a> <br /> <br/> <div id="comicLinks"> Comics I enjoy:<br/> <a href="http://threewordphrase.com/">Three Word Phrase</a>, <a href="http://oglaf.com/">Oglaf</a> (nsfw), <a href="http://www.smbc-comics.com/">SMBC</a>, <a href="http://www.qwantz.com">Dinosaur Comics</a>, <a href="http://www.asofterworld.com">A Softer World</a>, <a href="http://buttersafe.com/">Buttersafe</a>, <a href="http://pbfcomics.com/">Perry Bible Fellowship</a>, <a href="http://questionablecontent.net/">Questionable Content</a>, <a href="http://www.buttercupfestival.com/buttercupfestival.htm">Buttercup Festival</a> </div> <br/> Warning: this comic occasionally contains strong language (which may be unsuitable for children), unusual humor (which may be unsuitable for adults), and advanced mathematics (which may be unsuitable for liberal-arts majors).<br/> <br/> <h4>We did not invent the algorithm. The algorithm consistently finds Jesus. The algorithm killed Jeeves. <br />The algorithm is banned in China. The algorithm is from Jersey. The algorithm constantly finds Jesus.<br />This is not the algorithm. This is close.</h4><br/> <div class="line"></div> <br/> <div id="licenseText"> <!-- <a rel="license" href="http://creativecommons.org/licenses/by-nc/2.5/"><img alt="Creative Commons License" style="border:none" src="http://imgs.xkcd.com/static/somerights20.png" /></a><br/> --> This work is licensed under a <a rel="license" href="http://creativecommons.org/licenses/by-nc/2.5/">Creative Commons Attribution-NonCommercial 2.5 License</a>. <!-- <rdf:RDF xmlns="http://web.resource.org/cc/" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:dcterms="http://purl.org/dc/terms/" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns "><Work rdf:about=""><dc:creator>Randall Munroe</dc:creator><dcterms:rightsHolder>Randall Munroe</dcterms:rightsHolder><dc:type rdf:resource="http://purl.org/dc/dcmitype/StillImage" /><dc:source rdf:resource="http://www.xkcd.com/"/><license rdf:resource="http://creativecommons.org/licenses/by-nc/2.5/" /></Work><License rdf:about="http://creativecommons.org/licenses/by-nc/2.5/"><permits rdf:resource="http://web.resource.org/cc/Reproduction" /><permits rdf:resource="http://web.resource.org/cc/Distribution" /><requires rdf:resource="http://web.resource.org/cc/Notice" /><requires rdf:resource="http://web.resource.org/cc/Attribution" /><prohibits rdf:resource="http://web.resource.org/cc/CommercialUse" /><permits rdf:resource="http://web.resource.org/cc/DerivativeWorks" /></License></rdf:RDF> --> <br/> This means you"re free to copy and share these comics (but not to sell them). <a href="/license.html">More details</a>.<br/> </div> </div> </div> </div> <div class="ft"><div class="c"></div></div> </div> </div> </div> </body> </html> '
except:
return ""
return ""
def get_next_target(page):
start_link = page.find('<a href=')
if start_link == -1:
return None, 0
start_quote = page.find('"', start_link)
end_quote = page.find('"', start_quote + 1)
url = page[start_quote + 1:end_quote]
return url, end_quote
def union(p,q):
for e in q:
if e not in p:
p.append(e)
def get_all_links(page):
links = []
while True:
url,endpos = get_next_target(page)
if url:
links.append(url)
page = page[endpos:]
else:
break
return links
def crawl_web(seed):
tocrawl = [seed]
crawled = []
while tocrawl:
page = tocrawl.pop()
if page not in crawled:
union(tocrawl,get_all_links(get_page(page)))
crawled.append(page)
return crawled