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Web Scraping in Python 101

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Title Web Scraping in Python 101
Title of Series EuroPython 2014
Part Number 103
Number of Parts 120
Author Khalid, M.Yasoob
License CC Attribution 3.0 Unported:
You are free to use, adapt and copy, distribute and transmit the work or content in adapted or unchanged form for any legal purpose as long as the work is attributed to the author in the manner specified by the author or licensor.
DOI 10.5446/19995
Publisher EuroPython
Release Date 2014
Language English
Production Place Berlin

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Subject Area Computer Science
Abstract M.Yasoob Khalid - Web Scraping in Python 101 This talk is about web scraping in Python, why web scraping is useful and what Python libraries are available to help you. I will also look into proprietary alternatives and will discuss how they work and why they are not useful. I will show you different libraries used in web scraping and some example code so that you can choose your own personal favourite. I will also tell why writing your own scrapper in scrapy allows you to have more control over the scraping process. ----- Who am I ? ========= * a programmer * a high school student * a blogger * Pythonista * and tea lover - Creator of freepythontips.wordpress.com - I made soundcloud-dl.appspot.com - I am a main contributor of youtube-dl. - I teach programming at my school to my friends. - It's my first programming related conference. - The life of a python programmer in Pakistan What this talk is about ? ================== - What is Web Scraping and its usefulness - Which libraries are available for the job - Open Source vs proprietary alternatives - Whaich library is best for which job - When and when not to use Scrapy What is Web Scraping ? ================== Web scraping (web harvesting or web data extraction) is a computer software technique of extracting information from websites. - Wikipedia ###In simple words : It is a method to extract data from a website that does not have an API or we want to extract a LOT of data which we can not do through an API due to rate limiting. We can extract any data through web scraping which we can see while browsing the web. Usage of web scraping in real life. ============================ - to extract product information - to extract job postings and internships - extract offers and discounts from deal-of-the-day websites - Crawl forums and social websites - Extract data to make a search engine - Gathering weather data etc Advantages of Web scraping over using an API ======================== - Web Scraping is not rate limited - Anonymously access the website and gather data - Some websites do not have an API - Some data is not accessible through an API etc Which libraries are available for the job ? ================================ There are numerous libraries available for web scraping in python. Each library has its own weaknesses and plus points. Some of the most widely known libraries used for web scraping are: - BeautifulSoup - html5lib - lxml - re ( not really for web scraping, I will explain later ) - scrapy ( a complete framework ) A comparison between these libraries ============================== - speed - ease of use - what do i prefer - which library is best for which purpose Proprietary alternatives ================== - a list of proprietary scrapers - their price - are they really useful for you ? Working of proprietary alternatives =========================== - how they work (render javascript) - why they are not suitable for you - how custom scrapers beat proprietary alternatives Scrapy ======= - what is it - why is it useful - asynchronous support - an example scraper
Keywords EuroPython Conference
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EuroPython 2014
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so was what I would like to thank the organisers Europe-wide give me a chance to staring speaking for a few so my talk today is the scripting in Python and 1 so if you are already experienced with scraping so it is not the right place for you to be good so 1 1
so plus well and it would encourage want me I'm the harmony of the holidays I'm a programmer
or high school strength of blogger fathers and either so my experience I create all 3 parts and dates I made up of of source programs all just where you
have OK so there's a couple of open source programs I'm part we're going to use to be it's a dollar for videos with sports almost yeah it was exciting the reduced
form and finally the foreground was school and that's what my friends and this is my poster conference so we decided
to be about to start with reading the library desirable for for this job in Python and which library is better for which jobs I will also give the greatly and some of its internal and when I have altered you when and when not to use so what is the scraping webscraping with policy or whether extraction is a computer software technique that of extracting information from websites use these software programs in the human exploration of the world by Web by either implementing those are hybrid extract vertical or ending a fully-fledged brothers that is in the explorer most of our courses so that the Wikimedia less come to my understanding of so in similar words is the methods and therefore website that does not have an API on everyone would spend a lot of data which he cannot 20 to rectum some website along so this amount qualitative and making the API so if we want to spend a lot of data than with you cannot do that when EPA so you
have to focus on which fearing for that purpose and would strengthen wouldn't expect any that the way in which you can see was surfing the web
so the users of with living in real life there are more of use cases of enslavement we can extract of the bright information job postings and we can expect offers a discontinuity of the sites we can extract information from duration of sites with and what was forums and social site expect the reasserting and just like Google Yahoo and finally connects better weather up and do that just some use cases there are a lot of other use cases as well so that want itself with effect on using an ABI fossil was revealed some pretty image you can use site this IP addresses for describing a cycling reduced broadening of ideas resists it is anonymous you cannot optimize miss the existing website
put on it you can some of us might have an API for example give and have an API for some years ago so you can only use with very good said there from Wikipedia and some that are not accessible to any of like some for due due to the use you do stipulate cannot exist and are you out of the video so does and before joining anymore
so essential parts which the western influence them basic workflow you have to to get get the website using an is the library you have the possibility of a document using a parsing library then you have to store the result for work for the use and analyze Asian I'll focus more on parts and what is the main modeling and scraping so the libraries available for a job and by this basically these body parts in libraries but what we have here fulfilled Elizabeth readers a regular expressions library of Python is not really worth living in a time of and that regards and others things that later last we have the abuse of Cleveland with framework of Western framework may bipedal Hoffman the souls of digital libraries for for that purpose we have the request libraries you can submit a request or the URL and an artist you know you have this find then you can either use during 11 relative to and history of the poorer open the urine and and are and find you can use as we live and distributed tho if you want to book models but most of the time when there is the best 1 for this purpose then we have a lot libraries but for the beautiful so it's really easy to the beautiful API you considered a beautiful so often that involvement as the argument and then you going to work for them to directly using simply got title to get the Tigers or people that the dead then we have an XML you can severely examined articulable from strings Boston data government as spring then you have some of last class extracted from the document finally have regular expressions you can simply really got find already to read or mind and then Boston the regular it's background and actually document so let's focus on them in a little bit more detail 1st was beautiful so because of the usual API you can just to find and find all and it's all that just the find that there and find on that it's really easy to use it can handle broken market really easy to a lot of its size not have a proper model is model so if if
you what was a website which does not know what remarkable you should use because began in the world market is purely in Python but it's really slow so most of the body regard refusal and production preparation so
we have an estimate the edit summary exotic will give rise but on a findings for the C libraries also it's to and accessibility without signifies in the in the this is a wrapper around C libraries it's really fast it's not really Python and this binding for the C libraries is of New York by the requirement so when have started data support
and XML in the big names right now to support within the beam and exploring to other libraries examined as well as all other region from the 143 . 3 origin city when for there's this that so it is where right now
then we have another expression of the re libraries is the part of the standard library is so we decided for Python is usually to extract money would amount of text and on the human body is not possible with regular expressions is unpopularity if you do it was it was it was to learn a symbols which generated different like thought this very bother signed a prepared that's the best of the view that such as that that the energy and y component you have to combine all those symbols and then you have a of the paper and within the document is a better from documents however it is purely based Python with by that uses about the standard library is a very fast I will show that the end what everybody conversion from the 1 for gold we went for they're not comprise of the food so we had a similar evidence simply as that wasn't of 3 libraries all and that as we find that this was a local 1851 milliseconds the lesson I go to a table MS and rejects the 7 ms just deposit ideas from a given document so we can conclude that the medical play x more time than and little book 45 takes more time than we still if you wanted to kind of information is
avoided regular expressions so
what you do when your script needs are hot you want to spend millions of web pages everyday like to you want to make a broad view of but you want to do something they sorely tested so is a solution we have those solutions you can deploy your own custom-made forever are either you can use of framework like baby soul of this once
created while the fully tested framework is really fast it's a full blown away from logistic framework assessing synchronized you can make a lot of progress in Brazil is easy to use is everything you need a frustrated from the Institut libraries for the parsing libraries buddhist story libraries and not so hard especially compared to usual to or and it simmered here is also an editor of library for parsing spirit is an application framework for writing web scraper they call websites and took out from them in other words compared the full so not use the recycle bin ginger general I want you know what you're doing General this experiment since that sold but the main major negative point about maybe that it only by the the 1 cell the clockwise 3 point
x the main reason for that is that is based on the statement working library there already working on getting wanted support for research so investigates the 3 point x support services on the we so when
use greatly when you have percentages of pages when you want synchronous support offered blocks and you don't want to reinvent the wheel and when you're not afraid to learn something new so there's a beautiful court I ran across recently if you're not willing to risk that and you shows you will have to settle for the ordinary but Jim wrong so starting off with baby the local and global is very simple 1st all you have define a scraper defined I think you're going to extract from the doctors your document divided by the pipeline is optional is just for the data and value people of just demonstrate the basic building
blocks of starving because I don't have enough time to write a paper and where in the previous but is quite a spider so if you see that as part of the great is the same so it is in this spirit
1 so it right handed 1 inclusive and user-generated of basic skeleton off paper just went babies they start with this the product name here if the degree so you get the point that the structure of the configuration file and the back is with items required 500 settings or by and in this part of the order of what can inevitable spiders so what is the item items are that will be loaded with this data there were quite simple Python dictionaries but provide additional protection against populating undeclared fees preparing bibles so you know which then you're going to store and which you're not going to start sort of playing item clusters very simple just as important gradient then define a class it's is the 1 item is taken from the previous talk about real justice I've defined by the link and description so we don't really is simple it's really simple if you want to made for the misclassified quality than Boston of arguments whose very so 2nd that you can if you want to note that your and your X plus you can simply use this very handy pool that's the only scary issue for the sample you can simply but there is this shows that is the you out on that you want to test explodes this gave will open session for you it very white explores the is selected and we expect that the aforementioned document it's taken that either using explores really simple as the explores brackets that's spot and then use people would expect and that's it that's what it's about using screw the so right and the
left neighbor aspiring to is a
clustering by the user we therefore websites writing is very easy just follow these days before the end of last year we don't try to define the structure of this the list from which the yours part start 1 and then you have to define Boston with the intifada that is how you want to store the data and bottom so here a list the first you have all the right the name the spider in the class the name is required to run the spider later on the larger means so that you're scared but does not deviate from they're quite demanding the the stock so that define and also with the start stripping then there is a fast method and there's a little bit more on the response and then you just find it in the title is the end of the year and then you have to the items and that so only the very part large of you have yet to find a stable you can just scabies it's probably the most beginning the project forward so storing this period of here we have 2 choices 1st of all we can either use the export it's really simple this so that have based on the the usage of defined suddenly we have the identified and it allows you to customize the way you data script that I thought so using the exported and we can simply use previously was with the mask and we simply have add mindful with several of and then the final review prospects for the states that are either by the use of separate topic and will be covered in the future if you want to read on that is always there would also have really good information there when not use there so what you have to keep in mind when using stable if you just want to make a torus give don't use gradient if wanted was small number of pages he had huge no need to use credit because it is really useful if you want it was if you
want to make something simple that don't gravity is what remained of the the model and the basics and make a point composed babies good so what
should you use so if you want to make a script that does not have to expect a lot of information and if you're not afraid of learning something new and then use regular expressions you did you should use them only if you wanted to my new amount of information from a web page if you want to extract a lot of data and a lot of pure Python library requirement you elect a man is really fast if you want to extract information from broken model then you can have a set of the Hitler and if you want to save a lot of pages and want to use make sure framework the news pretty so what do I to be speeding up at regular expressions and maybe I started web-scraping with beautiful so as was the easiest and all these also questions that it maybe as a beautiful so as the preferred solution that I'm using let's ML and funded to really slow at all intuitive but as they took a
lot of time and they it's then I use regular expressions for some time interval in love with it for its feet and now you really only to make large of it was or when you go aloft the ones they use very good it's scale 69 thousand directly from website so knowledge of
what you do we'll it's a program I do and it also uses web-scraping and back in is applied bed laughter download videos and music from rates of sites like Facebook YouTube Vimeo Dailymotion management almost the animal website so well that was there I hope you learned something from the but what from the star so it was the 1st conference so forgive me for any mistakes and if you want to talk to me just meeting outside is want lost something they don't hesitate and I will try to answer it's funny questions up and I my father of
households that have plenty of time for questions and it I mean 1
challenging thing in in using the scrapping scrap is that let's say there is a change in the it's channel of dumb structure of of of finding websites I mean is there any like an exception handling I mean we can use to detect changing and the some structure of the web site and how we thought about the 100 such cases the
gold if you use anything from library you will have to see if a Markov chain is used there will break and remarks savings for that you have some changes there would be from the change of the site so those 2 things nor any other the process to happen the final state of you what do you mean the set your IP address so if I decide of right is we have some we can use around was you then we can use either addition or you can use the part work there some websites and effects affected a lot of the state through their demand they have high prediction you
can buy a lot of these and then predict the ideas that's the only way you can buy 1 you know there's a lot of yeah simply have yet mean
there user besides the I let it go the uh somewhat related questions desperately have any kind of arrangement and support for example I don't want to build sites and I don't care much small latencies so I want to write in my step into 1 place the 2nd the argument that there is often the configuration file you can limit harmony with it is you want to open in parallel you can either or 1 biggest or you can use 1 page if you want 1 based you can also consider option value again just give a moving involving and the based like what if you want to wait for opening the next stage and you want to put a lot of if you don't want with a Lord on those so you can use those sentences from below the negative point of that greatly don't the sport free but for and ones which is what we by than 3 which is evidence for dark the question never been that way it already has 60 per cent support for by the 3 of them while they're going to achieve the muscle and some couple of months so I will spare will be there and what questions and yet 1 1 question how do you deal with pages that all purely based on phase to render the page with JavaScript and what is your around it is that he uses the phone off right here so what is your suggestion that those of I work with that problem is that you can use simply equal inspect and is that there is a direct cause you can go because it explores you see there's the API you can make a pattern of the API euros and impossible to a was baby and you will see you're it also mediados again iodide HTML form any more questions no then much again and that rest of
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