The problem
I'm using the Wikipedia API to get page HTML which I parse. I use queries like this one to get the HTML for the first section of a page.
The MediaWiki API provides a handy parameter, redirects, which will cause the API to automatically follow pages that redirect other pages. For example, if I search for 'Cats' with https://en.wikipedia.org/w/api.php?page=Cats&redirects, I will be shown the results for Cat because Cats redirects to Cat.
I'd like a similar function for disambiguation pages such as this, by which if I arrive at a disambiguation page, I am automatically redirected to the first link. For example, if I make a request to a page like Mercury, I'd automatically be redirected to Mercury (element), as it is the first link listed in the page.
The Python HTML parser BeautifulSoup is fairly slow on large documents. By only requesting the first section of articles (that's all I need for my use), using section=0, I can parse it quickly. This is perfect for most articles. But for disambiguation pages, the first section does not include any of the links to specific pages, making it a poor solution. But if I request more than the first section, the HTML loading slows down, which is unnecessary for most articles. See this query for an example of a disambiguation page in which links are not included in the first section.
What I have so far
As of right now, I've gotten as far as detecting when a disambiguation page is reached. I use code like
bs4.BeautifulSoup(page_html).find("p", recursive=false).get_text().endswith(("refer to:", "refers to:"))
I also spent a while trying to write code that automatically followed a link, before I realized that the links were not included in
My constraints
I'd prefer to keep the number of requests made to a minimum. I also need to be parsing as little HTML as possible, because speed is essential for my application.
Possible solutions (which I need help executing)
I could envision several solutions to this problem:
A way within the MediaWiki API to automatically follow the first link from disambiguation pages
A method within the Mediawiki API that allows it to return different amounts of HTML content based on a condition (like presence of a disambiguation template)
A way to dramatically improve the speed of bs4 so that it doesn't matter if I end up having to parse the entire page HTML
As Tgr and everybody said, no, such a feature doesn't exist because it doesn't make sense. The first link in a disambiguation page doesn't have any special status or meaning.
As for the existing API, see https://www.mediawiki.org/wiki/Extension:Disambiguator#API_usage
By the way, the "bot policy" you linked does not really apply to crawlers/scraper; the only relevant policy/guideline is the User-Agent policy.
Related
I am trying to scrape a web site using python and beautiful soup. I encountered that in some sites, the image links although seen on the browser is cannot be seen in the source code. However on using Chrome Inspect or Fiddler, we can see the the corresponding codes.
What I see in the source code is:
<div id="cntnt"></div>
But on Chrome Inspect, I can see a whole bunch of HTML\CSS code generated within this div class. Is there a way to load the generated content also within python? I am using the regular urllib in python and I am able to get the source but without the generated part.
I am not a web developer hence I am not able to express the behaviour in better terms. Please feel free to clarify if my question seems vague !
You need JavaScript Engine to parse and run JavaScript code inside the page.
There are a bunch of headless browsers that can help you
http://code.google.com/p/spynner/
http://phantomjs.org/
http://zombie.labnotes.org/
http://github.com/ryanpetrello/python-zombie
http://jeanphix.me/Ghost.py/
http://webscraping.com/blog/Scraping-JavaScript-webpages-with-webkit/
The Content of the website may be generated after load via javascript, In order to obtain the generated script via python refer to this answer
A regular scraper gets just the HTML document. To get any content generated by JavaScript logic, you rather need a Headless browser that would also generate the DOM, load and run the scripts like a regular browser would. The Wikipedia article and some other pages on the Net have lists of those and their capabilities.
Keep in mind when choosing that some previously major products of those are abandoned now.
TRY THIS FIRST!
Perhaps the data technically could be in the javascript itself and all this javascript engine business is needed. (Some GREAT links here!)
But from experience, my first guess is that the JS is pulling the data in via an ajax request. If you can get your program simulate that, you'll probably get everything you need handed right to you without any tedious parsing/executing/scraping involved!
It will take a little detective work though. I suggest turning on your network traffic logger (such as "Web Developer Toolbar" in Firefox) and then visiting the site. Focus your attention attention on any/all XmlHTTPRequests. The data you need should be found somewhere in one of these responses, probably in the middle of some JSON text.
Now, see if you can re-create that request and get the data directly. (NOTE: You may have to set the User-Agent of your request so the server thinks you're a "real" web browser.)
I am new to Python and web crawling. I intend to scrape links in the top stories of a website. I was told to look at to its Ajax requests and send similar ones. The problem is that all requests for the links are same: http://www.marketwatch.com/newsviewer/mktwheadlines
My question would be how to extract links from an infinite scrolling box like this. I am using beautiful soup, but I think it's not suitable for this task. I am also not familiar with Selenium and java scripts. I know how to scrape certain requests by Scrapy though.
It is indeed an AJAX request. If you take a look at the network tab in your browser inspector:
You can see that it's making a POST request to download the urls to the articles.
Every value is self explanatory in here except maybe for docid and timestamp. docid seems to indicate which box to pull articles for(there are multiple boxes on the page) and it seems to be the id attached to <li> element under which the article urls are stored.
Fortunately in this case POST and GET are interchangable. Also timestamp paremeter doesn't seem to be required. So in all you can actually view the results in your browser, by right clicking the url in the inspector and selecting "copy location with parameters":
http://www.marketwatch.com/newsviewer/mktwheadlines?blogs=true&commentary=true&docId=1275261016&premium=true&pullCount=100&pulse=true&rtheadlines=true&topic=All%20Topics&topstories=true&video=true
This example has timestamp parameter removed as well as increased pullCount to 100, so simply request it, it will return 100 of article urls.
You can mess around more to reverse engineer how the website does it and what the use of every keyword, but this is a good start.
I'm trying to use scrapy to get content rendered only after a javascript: link is clicked. As the links don't appear to follow a systematic numbering scheme, I don't know how to
1 - activate a javascript: link to expand a collapsed panel
2 - activate a (now visible) javascript: link to cause the popup to be rendered so that its content (the abstract) can be scraped
The site https://b-com.mci-group.com/EventProgramme/EHA19.aspx contains links to abstracts that will be presented at a conference I plan to attend. The site's export to PDF is buggy, in that it duplicates a lot of data at PDF generation time. Rather than dealing with the bug, I turned to scrapy only to realize that I'm in over my head. I've read:
Can scrapy be used to scrape dynamic content from websites that are using AJAX?
and
How to scrape coupon code of coupon site (coupon code comes on clicking button)
But I don't think I'm able to connect the dots. I've also seen mentions to Selenium, but am not sure that I must resort to that.
I have made little progress, and wonder if I can get a push in the right direction, with the following information in hand:
In order to make the POST request that will expand the collapsed panel (item 1 above) I have a traced that the on-page JS javascript:ShowCollapsiblePanel(116114,1695,44,191); will result in a POST request to TARGETURLOFWEBSITE/EventSessionAjaxService/GetSessionDetailsHtml with payload:
{"eventSessionID":116114,"eventSessionWebSiteSetupViewID":191}
The parameters for eventSessionID and eventSessionWebSiteSetupViewID are clearly in the javascript:ShowCollapsiblePanel text.
How do I use scrapy to iterate over all of the links of form javascript:ShowCollapsiblePanel? I tried to use SgmlLinkExtractor, but that didn't return any of the javascript:ShowCollapsiblePanel() links - I suspect that they don't meet the criteria for "links".
UPDATE
Making progress, I've found that SgmlLinkExtractor is not the right way to go, and the much simpler:
sel.xpath('//a[contains(#href, "javascript:ShowCollapsiblePanel")]').re('((\d+)\,(\d+)\,(\d+)\,(\d+)')
in scrapy console returns me all of the numeric parameters for each javascript:ShowCollapsiblePanel() (of course, right now they are all in one long string, but I'm just messing around in the console).
The next step will be to take the first javascript:ShowCollapsiblePanel() and generate the POST request and analyze the response to see if the response contains what I see when I click the link in the browser.
I fought with a similar problem and after much pulling out hair I pulled the data set I needed with import.io which has a visual type scraper but it's able to run with javascript enabled which did just what I needed and it's free. There's also a fork on git hub I saw last night of scrapy that looked just like the import io scraper it called ..... give me a min
Portia but I don't know if it'll do what you want
https://codeload.github.com/scrapinghub/portia/zip/master
Good
Say I look at the following Tumblr post: http://ronbarak.tumblr.com/post/40692813…
It (currently) has 292 notes.
I'd like to get all the above notes using a Python script (e.g., via urllib2, BeautifulSoup, simplejson, or tumblr Api).
Some extensive Googling did not produce any items relating to notes' extraction in Tumblr.
Can anyone point me in the right direction on which tool will enable me to do that?
Unfortunately looks like the Tumblr API has some limitations (lacks of meta information about Reblogs, notes limited by 50), so you can't get all the notes.
It is also forbidden to do page scraping according to the Terms of Service.
"You may not do any of the following while accessing or using the Services: (...) scrape the Services, and particularly scrape Content (as defined below) from the Services, without Tumblr's express prior written consent;"
Source:
https://groups.google.com/forum/?fromgroups=#!topic/tumblr-api/ktfMIdJCOmc
Without JS you get separate pages that only contain the notes. For the mentioned blog post the first page would be:
http://ronbarak.tumblr.com/notes/40692813320/4Y70Zzacy
Following pages are linked at the bottom, e.g.:
http://ronbarak.tumblr.com/notes/40692813320/4Y70Zzacy?from_c=1358403506
http://ronbarak.tumblr.com/notes/40692813320/4Y70Zzacy?from_c=1358383221
http://ronbarak.tumblr.com/notes/40692813320/4Y70Zzacy?from_c=1358377013
…
(See my answer on how to find the next URL in a’s onclick attribute.)
Now you could use various tools to download/parse the data.
The following wget command should download all notes pages for that post:
wget --recursive --domains=ronbarak.tumblr.com --include-directories=notes http://ronbarak.tumblr.com/notes/40692813320/4Y70Zzacy
Like Fabio implies, it is better to use the API.
If for whatever reasons you cannot, then the tools you will use will depend on what you want to do with the data in the posts.
for a data dump: urllib will return a string of the page you want
looking for a specific section in the html: lxml is pretty good
looking for something in unruly html: definitely beautifulsoup
looking for a specific item in a section: beautifulsoup, lxml, text parsing is what you need.
need to put the data in a database/file: use scrapy
Tumblr url scheme is simple: url/scheme/1, url/scheme/2, url/scheme/3, etc... until you get to the end of the posts and the servers just does not return any data anymore.
So if you are going to brute force your way to scraping, you can easily tell your script to dump all the data on your hard drive until, say the contents tag, is empty.
One last word of advice, please remember to put a small sleep(1000) in your script, because you could put some stress on Tumblr servers.
how to load all notes on tumblr? also covers the topic, but unor's response (above) does it very well.
Hi guys : Is there a way to improve trac wiki quality using a plugin that deals with artifacts like for obsolete pages, or pages that refer to code which doesn't exist anymore, pages that are unlinked, or pages which have a low update-rate ? I think there might be several heuristics which could be used to prevent wiki-rot :
Number of recent edits
Number of recent views
Wether or not a page links to a source file
Wether or not a wiki page's last update is < or > the source files it links to
Wether entire directories in the wiki have been used/edited/ignored over the last "n" days
etc. etc. etc.
If nothing else, just these metrics alone would be useful for each page and each directory from an administrative standpoint.
I don't know of an existing plugin that does this, but everything you mentioned certainly sounds do-able in one way or another.
You can use the trac-admin CLI command to get a list of wiki pages and to dump the contents of a particular wiki page (as plain text) to a file or stdout. Using this, you can write a script that reads in all of the wiki pages, parses the content for links, and generates a graph of which pages link to what. This should pinpoint "orphans" (pages that aren't linked to), pages that link to source files, and pages that link to external resources. Running external links through something like wget can help you identify broken links.
To access last-edited dates, you'll want to query Trac's database. The query you'll need will depend on the particular database type that you're using. For playing with the database in a (relatively) safe and easy manner, I find the WikiTableMacro and TracSql plugins quite useful.
The hardest feature in your question to implement would be the one regarding page views. I don't think that Trac keeps track of page views, you'll probably have to parse your web server's log for that sort of information.
How about these:
BadLinksPlugin: This plugin logs bad local links found in wiki content.
It's a quite new one, just deals with dangling links, but any bad links as I see from source code. This is at least one building block to your solution request.
VisitCounterMacro: Macro displays how many times was wiki page displayed.
This is a rather old one. You'll get just the statistic per page while an administrative view is missing, but this could be built rather easily, i.e. like a custom PageIndex.