# \[SoC\] Ariel 0.1.0 released **URL:** \ **Category:** Ruby\ **Created:** [August 22, 2006, 9:37pm UTC](https://www.ruby-forum.com/t/soc-ariel-0-1-0-released/66013 "2006-08-22T21:37:39Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![ASSSBradbury](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/4af34b/32.png) [@ASSSBradbury](https://www.ruby-forum.com/u/ASSSBradbury)\ **Post date:** [August 22, 2006, 9:37pm UTC](https://www.ruby-forum.com/t/soc-ariel-0-1-0-released/66013/1 "2006-08-22T21:37:39Z")
= Ariel release 0.1.0 == About - Ariel: A Ruby I.rmation Extraction Library Ariel is a library that allows you to extract information from semi-structured documents (such as websites). It is different to existing tools because rather than expecting the developer to write rules to extract the desired information, Ariel will use a small number of labeled examples to generate and learn effective extraction rules. It is developed by Alex Bradbury and released under the MIT license. Ariel was started as a Google Summer of Code project mentored by Austin Z. in 2006. == Install gem install ariel == Announcement I’m happy to announce the release of Ariel 0.1.0, the result of my Summer of Code work. This release should be easy to use, very functional, and hopefully useful - so it’s worth trying out. I’ve put a lot of effort in to writing clear and straightforward documentation to get your started, so take a look at the docs available at [http://ariel.rubyforge.org](http://ariel.rubyforge.org). In particular, flick through the tutorial and quick start guide. If you’re interested, you may also want to take a look at the theory page where I’ve made a good start on describing the method Ariel uses to learn extraction rules. If you have any problems or find any bugs, just send me an email or add it to the issue tracker (see link below). Enjoy. See the FAQ for a vim snippet to make labeling examples a little easier. == Quickstart/Basic usage - @require ‘ariel’@ - Define a structure for the information you wish to extract: structure = Ariel::Node::Structure.new do |r| r.item :title r.item :body r.list :comments do |c| c.list\_item :comment do |d| d.item :author d.item :body end end end - Collect a few examples of the sort of document you wish to extract information from (pages from the same website for instance). - Label each example with tags such as \, \ and so on in the relevant places. - Ariel.learn structure, labeled\_file1, labeled\_file2, labeled\_file3 - Find the documents you want to extract information from. - extractions = Ariel.extract structure, unlabeled\_file1, unlabeled\_file2 - extractions[0].search(‘comments/\*/body’).each {|e| puts e.extracted\_text} =\> “Great stuff, loving it”, “I love life”, … - extractions[0].at(‘comments/34’) =\> nil (there is no 34th comment, #at returns the first result rather than an array of matches). == Credits Ariel is developed by Alex Bradbury as a Google Summer of Code project under the mentoring of Austin Z… == Links SVN Repository: [http://rubyforge.org/projects/ariel](http://rubyforge.org/projects/ariel) Issue tracker: [http://code.google.com/p/ariel/issues/](http://code.google.com/p/ariel/issues/) Documentation/homepage: [http://ariel.rubyforge.org](http://ariel.rubyforge.org) RDoc: [http://ariel.rubyforge.org/rdoc/](http://ariel.rubyforge.org/rdoc/) ---
**Author:** ![ASSSBradbury](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/4af34b/32.png) [@ASSSBradbury](https://www.ruby-forum.com/u/ASSSBradbury)\ **Post date:** [August 23, 2006, 3:10am UTC](https://www.ruby-forum.com/t/soc-ariel-0-1-0-released/66013/2 "2006-08-23T03:10:19Z")
Very impressive library! I remember when you posted about this at the beginning of the summer. I took the library and pointed it at the USCCBs online version of the Bible and got some very impressive results! It was able to identify book, chapter and verse with only a few examples. With only 3 sample pages, and the following structure I was able to get very reliable results structure = Ariel::Node::Structure.new do |r| r.item :book do |b| b.item :title b.item :chapter do |c| c.item :title c.list :verses do |v| v.list\_item :verse end end end end I was particularly impressed that it understood how I re-used the title tag in different contexts (i.e. for the book and chapter title). If you’d like me to email you my structure files, my examples, and the tests I use them in I’d be glad to. It’s three small files but probably too much for the list. Comments and questions I jotted down while playing with this: - Most of the chapter pages have footnotes interspersed throughout the text. These are hyperlinks to anchors below the main body of the chapter. Can Ariel correctly identify footnotes and pull in the text for them? - Ariel gets confused if you have tags in the example document that are not in the structure, but look like Ariel tags. Example: I had a \ tag which contained \ tags. I realized ‘verses’ was not needed so removed the item definition from the structure but not the example file. Ariel was not able to find the verse items until I removed the \ tag. - Typing “extracted\_text” to get the text of each node is cumbersome. If its not already, maybe overload to\_s on nodes to display the text? - Dealing with items is a little cumbersome. To get the number of verses in a chapter, I have to type e[:book][:chapter][:verses].children.length. Since I am already treating the nodes like arrays, having a ‘length’ method would be nice: e[:book][:chapter][:verses].length - Better progress indication during learning phase. Hard to tell if program is hung or if it is managing to do something. The CPU is pegged but its hard to tell what progress is being made. - More info about the search/at methods and expressions they can take. RDOC and the tutorial only hint at what you can do. - Falls apart if tags entered are not well formed and gives little indication why. For example, I had missed an end tag on a list\_item. The program didnt use the examples provided (said “learning node X with 2 examples” when I had 3) and then would quit with the error “No examples are suitable for exhaustive rule learning” ---
**Author:** ![ASSSBradbury](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/4af34b/32.png) [@ASSSBradbury](https://www.ruby-forum.com/u/ASSSBradbury)\ **Post date:** [August 23, 2006, 11:06pm UTC](https://www.ruby-forum.com/t/soc-ariel-0-1-0-released/66013/3 "2006-08-23T23:06:36Z")
Hi, > = Ariel release 0.1.0 > > == About - Ariel: A Ruby I.rmation Extraction Library _WAY_ cool! Only one reply post just wasn’t enough I thought, very cool project indeed 🙂 Kash ---
**Author:** ![ASSSBradbury](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/4af34b/32.png) [@ASSSBradbury](https://www.ruby-forum.com/u/ASSSBradbury)\ **Post date:** [September 4, 2006, 2:46pm UTC](https://www.ruby-forum.com/t/soc-ariel-0-1-0-released/66013/4 "2006-09-04T14:46:09Z")
A. S. Bradbury wrote: > They’re very limited at the moment, there’s nothing more to them than listing > parameters between /, and \* are supported much like directory globbing. > There’s no way to specify certain parameters (like to select only verses > lists with more than 5 children). But then Ruby has powerful array operations > like #select and #reject for this sort of querying. I made this interface as > basic as possible, not being sure what people would need/use. What sort of > queries would you like to perform? I was planning on adding range selection, > so you could do e.search ‘book/chapter/verses/[0…5/whatever’. Clearly in > your structure it would be as easy to just slice the result array. If I look at the queries that can be performed now they look somewhat similar to XPath expressions. The structure you define also looks a lot like an XML structure, so maybe the data extracted can be easily converted to XML? This would allow you to use REXML’s powerful XPath support to query the results. Next to this the results can easily be exported as XML too. Regards, Peter ---
**Author:** ![ASSSBradbury](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/4af34b/32.png) [@ASSSBradbury](https://www.ruby-forum.com/u/ASSSBradbury)\ **Post date:** [September 4, 2006, 2:46pm UTC](https://www.ruby-forum.com/t/soc-ariel-0-1-0-released/66013/5 "2006-09-04T14:46:07Z")
On Wednesday 23 August 2006 00:25, Justin B. wrote: > Very impressive library! I remember when you posted about this at the > beginning of the summer. I took the library and pointed it at the > USCCBs online version of the Bible and got some very impressive > results! It was able to identify book, chapter and verse with only a > few examples. Thank you so much for taking the time for writing this detailed email. > ``` > end > end > > ``` > > end > end > > I was particularly impressed that it understood how I re-used the > title tag in different contexts (i.e. for the book and chapter title). This is because of the way it checks for nesting when extracting label tags, which is why it gets confused when you have an extra tag. \\…\…\\…\ When it encounters the first \, it increments the nesting level by one, and again when it encounters the first \. The two closing tags decrement it, and then when \ (which we’re searching for in this example) is encountered and the nesting level is 0, we know it’s the right one. > If you’d like me to email you my structure files, my examples, and the > tests I use them in I’d be glad to. It’s three small files but > probably too much for the list. Yes, please do email them to me. > Comments and questions I jotted down while playing with this: > > - Most of the chapter pages have footnotes interspersed throughout the > text. These are hyperlinks to anchors below the main body of the > chapter. Can Ariel correctly identify footnotes and pull in the text > for them? I’ll have to take a look at your examples, but if I understand correctly not really. Perhaps you can extract footnote references (as in #footnote34) from the relevant page section, and separately extract all footnotes (with a footnote.reference). Then you can match them up, is this what you’re trying to do? I haven’t thought about having linked items like that before…interesting. > - Ariel gets confused if you have tags in the example document that > are not in the structure, but look like Ariel tags. Example: I had a > \ tag which contained \ tags. I realized ‘verses’ > was not needed so removed the item definition from the structure but > not the example file. Ariel was not able to find the verse items until > I removed the \ tag. The checking and error reporting when parsing labeled documents isn’t that great at the moment, I’ll have to rework it a bit to make it easier to work out where there are errors if they exist. I’m not sure I follow here, you have :verses in your example above. Putting list items in a container is the recommended way of doing things: - Verse 1 - Verse 2 - Verse 3 You could put the \ right next to the first \ and the same with the \ if you wanted. When defining structure, you should really only put a list\_item as a single child of a list (internally a list is just an item…I mean if you think about it extracting the whole list above is the same as extracting any other piece of text that occurs once). If you have multiple list\_item’s at the same level I think you’d get a lot of things going wrong. I’ll add a check for this - a list\_item should have no siblings. > - Typing “extracted\_text” to get the text of each node is cumbersome. > If its not already, maybe overload to\_s on nodes to display the text? Will do this. > - Dealing with items is a little cumbersome. To get the number of > verses in a chapter, I have to type > e[:book][:chapter][:verses].children.length. Since I am already > treating the nodes like arrays, having a ‘length’ method would be > nice: e[:book][:chapter][:verses].length This is a case where I’d like you to use #search. It’s easier for you too - what if no value for chapter was extracted for whatever reason? You’d get an error with the code above (because you’d be using [] on the nil value returned by e[:book][:chapter]), but e.search(‘book/chapter/verses/_’).length would just return 0. (e/'book/chapter/verses/_’).length is equivalent. I guess I haven’t defined #size/#length because it makes sense when you’re talking about a list, but means little when you’re talking about e.chapter.size I think. #size = number of children seems reasonable enough though, I’ll add that. > - Better progress indication during learning phase. Hard to tell if > program is hung or if it is managing to do something. The CPU is > pegged but its hard to tell what progress is being made. You’re seeing at least messages like this?: info: Learning rules for node version\_history with 2 examples info: Learnt start rules [#\] You can fill your screen with status updates by using the -D switch if using the command line script, by setting $DEBUG or by Ariel::Log.set\_level :debug It’s hard to know what status information to output. Other than printing the name of the item we’re learning rules for and the rules as they’re learnt, I’m not sure what else would mean something to the user who isn’t familiar with Ariel internals and wouldn’t be too excessively verbose. If you just want to know something’s going on behind the scenes, then try one of the switches above. > - More info about the search/at methods and expressions they can take. > RDOC and the tutorial only hint at what you can do. They’re very limited at the moment, there’s nothing more to them than listing parameters between /, and \* are supported much like directory globbing. There’s no way to specify certain parameters (like to select only verses lists with more than 5 children). But then Ruby has powerful array operations like #select and #reject for this sort of querying. I made this interface as basic as possible, not being sure what people would need/use. What sort of queries would you like to perform? I was planning on adding range selection, so you could do e.search ‘book/chapter/verses/[0…5/whatever’. Clearly in your structure it would be as easy to just slice the result array. This is where I could really use some practical examples to beef out the documentation. Maybe some of the functionalities people might want are easily provided using Ruby’s standard library, but the documentation should give pointers on where to look, and suggest useful techniques. > - Falls apart if tags entered are not well formed and gives little > indication why. For example, I had missed an end tag on a list\_item. > The program didnt use the examples provided (said “learning node X > with 2 examples” when I had 3) and then would quit with the error “No > examples are suitable for exhaustive rule learning” Mentioned this problem with error reporting above. I’ve added it to the issue tracker, this is definitely something that makes Ariel less user friendly. Can you recreate this with one of your labeled files? The message only learning node x with 2 examples when there are 3 seems a little odd. The “No examples are suitable for exhaustive rule learning” takes a little bit of explaining, that I probably don’t have time to do properly. But basically, taking the example I used above. I could have labeled it like this: - Verse 1 - Verse 2 - Verse 3 Remember how Ariel learns rules - it finds a rule that consumes all the tokens up to the one that is labeled. Assume we’re finding start rules (end rules have the same issue), there are no tokens between the beginning of the extracted verses list and the label. So the only possible rule is an empty rule with no landmarks, which of course can’t be applied exhaustively to iterate over the whole list. This is why this example must be ignored in the current (somewhat naive) implementation. I find it works pretty well, it just could be better. Looking in to this is one of my post-SoC aims. A problem with lists is that you don’t want to make users label every item, or even count them. The good thing is that lists are generally very regular and have simple rules to split them. Returning to the example, if we can’t make a start rule that locates the start of the first verse, then how do we extract it? The answer is the end rule, say we have an end rule that has as a landmark, the lowest end location will have a position less than the first start location, so Ariel assumes that all tokens from the first to the lowest end location are a list item. Hope that makes a little sense. This isn’t something I’ve explained much/at all in the documentation, because it requires quite a lot of understanding of how Ariel works, and I’m hoping to look at ways to change the way this works. Thanks so much again for taking the time to look through my project and share your experiences, hope my response has been some help. Apologies if it’s a little long. Regards, Alex ---
**Author:** ![ASSSBradbury](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/4af34b/32.png) [@ASSSBradbury](https://www.ruby-forum.com/u/ASSSBradbury)\ **Post date:** [September 4, 2006, 2:46pm UTC](https://www.ruby-forum.com/t/soc-ariel-0-1-0-released/66013/6 "2006-09-04T14:46:09Z")
On Wednesday 23 August 2006 22:35, Peter C. Verhage wrote: > > be as easy to just slice the result array. > > If I look at the queries that can be performed now they look somewhat > similar to XPath expressions. The structure you define also looks a lot > like an XML structure, so maybe the data extracted can be easily > converted to XML? This would allow you to use REXML’s powerful XPath > support to query the results. Next to this the results can easily be > exported as XML too. I hadn’t got round to XML export yet, but this seems like an excellent reason to bump it up higher on the todo list. I wanted to avoid reimplementing XPath, which is why I chose a very simple query interface that is quite similar to globbing directories (no \*\* at the moment). XML export of course means I don’t have to reimplement this myself, excellent. I’ll add #to\_xml to the extracted data structures. Alex