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• Python KMeans clustering words

  - by sadawd

  Dear Everyone I am interested to perform kmeans clustering on a list of words with the distance measure being Leveshtein. 1) I know there are a lot of frameworks out there, including scipy and orange that has a kmeans implementation. However they all require some sort of vector as the data which doesn't really fit me. 2) I need a good clustering implementation. I looked at python-clustering and realize that it doesn't a) return the sum of all the distance to each centroid, and b) it doesn't have any sort of iteration limit or cut off which ensures the quality of the clustering. python-clustering and the clustering algorithm on daniweb doesn't really work for me. Can someone find me a good lib? Google hasn't been my friend

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• string categorization strategies

  - by Andrew Heath

  I'm the one-man dev team on a fledgling military history website. One aspect of the site is a catalog of ~1,200 individual battles, including the nations & formations (regiments, divisions, etc) which took part. The formation information (as well as the other battle info) was manually imported from a series of books by a 10-man volunteer team. The formations were listed in groups with varying formatting and abbreviation patterns. At the time I set up the data collection forms I couldn't think of a good way to process that data... and elected to store it all as strings in the MySQL database and sort it out later. Well, "later" - as it tends to happen - has arrived. :-) Each battle has 2+ records in the database - one for each nation that participated. Each record has a formations text string listing the formations present as the volunteer chose to add them. Some real examples: 39th Grenadier Rgmt, 26th Volksgrenadier Division 2nd Luftwaffe Field Division, 246th Infantry Division 247th Rifle Division, 255th Tank Brigade 2nd Luftwaffe Field Division, SS Cavalry Division 28th Tank Brigade, 158th Rifle Division, 135th Rifle Division, 81st Tank Brigade, 242nd Tank Brigade 78th Infantry Division 3rd Kure Special Naval Landing Force, Tulagi Seaplane Base personnel 1st Battalion 505th Infantry Regiment The ultimate goal is for each individual force to have an ID, so that its participation can be traced throughout the battle database. Formation hierarchy, such as the final item above 1st Battalion (of the) 505th Infantry Regiment also needs to be preserved. In that case, 1st Battalion and 505th Infantry Regiment would be split, but 1st Battalion would be flagged as belonging to the 505th. In database terms, I think I want to pull the formation field out of the current battle info table and create three new tables: FORMATION [id] [name] FORMATION_HIERARCHY [id] [parent] [child] FORMATION_BATTLE [f_id] [battle_id] It's simple to explain, but complicated to enact. What I'm looking for from the SO community is just some tips on how best to tackle this problem. Ideally there's some sort of method to solving this that I'm not aware of. However, as a last resort, I could always code a classification framework and call my volunteers back to sort through 2,500+ records...

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• How to calculate order (big O) for more complex algorithms (ie quicksort)

  - by bangoker

  I know there are quite a bunch of questions about big O notation, I have already checked Plain english explanation of Big O , Big O, how do you calculate/approximate it?, and Big O Notation Homework--Code Fragment Algorithm Analysis?, to name a few. I know by "intuition" how to calculate it for n, n^2, n! and so, however I am completely lost on how to calculate it for algorithms that are log n , n log n, n log log n and so. What I mean is, I know that Quick Sort is n log n (on average).. but, why? Same thing for merge/comb, etc. Could anybody explain me in a not to math-y way how do you calculate this? The main reason is that Im about to have a big interview and I'm pretty sure they'll ask for this kind of stuff. I have researched for a few days now, and everybody seem to have either an explanation of why bubble sort is n^2 or the (for me) unreadable explanation a la wikipedia Thanks!

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• Using Accelerometer in Wiimote for Physics Practicals

  - by Omar

  I have to develop some software in my school to utilize the accelerometer in the Wiimote for recording data from experiments, for example finding the acceleration and velocity of a moving object. I understand how the accelerometer values will be used but I am sort of stuck on the programming front. There is a set of things that I would like to do: Live streaming of data from the Wiimote via bluetooth Use the accelerometer values to find velocity and displacment via integration Plot a set of results Avoid the use of the infrared sensor on the Wiimote Please can anyone give me their thoughts on how to go about this. Also it would be great if people could direct me to existing projects that utizlise the wiimote. Also can someone suggest what would be the best programming language to use for this. My current bet is on using Visual basic. Any sort of help is greatly appretiated.

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• mysql birthday reminder, leap year

  - by moodh

  Hi, I'm trying to sort out a result set that gives the 5 closest users sorted by upcoming birthday. This works perfectly until leap years comes into play. For example: May 15th - 96 days left May 15th - 97 days left The top result is a birth at 1987 and the lower is from 1988. u_birth is stored as yyyy-mm-dd. Is there a simple way to sort this problem without having to rewrite the entire query? SELECT u_birth, IF( DAYOFYEAR( u_birth ) >= DAYOFYEAR( NOW() ), DAYOFYEAR( u_birth ) - DAYOFYEAR( NOW() ), DAYOFYEAR( u_birth ) - DAYOFYEAR( NOW() ) + DAYOFYEAR( CONCAT( YEAR( NOW() ), '-12-31' ) ) ) AS distance FROM (blog_users) WHERE `s_agehide` = 0 ORDER BY distance ASC LIMIT 5 This query is taken and modified from the mysql manual: http://dev.mysql.com/doc/refman/5.1/en/date-and-time-functions.html#c7489

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• Sorting an array in ascending order without losing the index Objective-C

  - by thary

  Hello all, I have an array for instance, Array { 3.0 at Index 0 2.0 at Index 1 3.5 at Index 2 1.0 at Index 4 } I would like to get sort it in ascending order without losing the index in the first place, like this, Array { 1.0 at Index 4 2.0 at Index 1 3.0 at Index 0 3.5 at Index 2 } When I sort the array using this, NSArray *sortedArray = [hArray sortedArrayUsingSelector:@selector(caseInsensitiveCompare:)]; [knnRecog sortUsingDescriptors:[NSArray arrayWithObject:sortAsc]]; I lose the index. Does anyone know a way to preserve the index after sorting the array? Thanks

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• Getting a sorted distinct list from mySQL

  - by Stomped

  Goal I'l like to get a list of unique FID's ordered by the the one which has most recently been changed. In this sample table it should return FIDs in the order of 150, 194, 122 Example Data ID FID changeDate ---------------------------------------------- 1 194 2010-04-01 2 122 2010-04-02 3 194 2010-04-03 4 150 2010-04-04 My Attempt I thought distinct and order by would do the trick. I initially tried: SELECT distinct `FID` FROM `tblHistory` WHERE 1 ORDER BY changeDate desc # Returns 150, 122, 194 using GROUP BY has the same result. I'm just barely a SQL amateur, and I'm a bit hung up. What seems to be happening is the aggregating functions find the first occurrence of each and then perform the sort. Is there a way I can get the result I want straight from mySQL or do I have to grab all the data and then sort it in the PHP?

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• "Cannot convert to IComparer"

  - by Odrade

  I have the following IComparer defined for boxed RegistryItem objects: public class BoxedRegistryItemComparer : IComparer<object> { public int Compare(object left, object right) { RegistryItem leftReg = (RegistryItem)left; RegistryItem rightReg = (RegistryItem)right; return string.Compare(leftReg.Name, rightReg.Name); } } I want to use this to sort an ArrayList of boxed RegistryItems (It really should be a List<RegistryItem, but that's out of my control). ArrayList regItems = new ArrayList(); // fill up the list ... BoxedRegistryItemComparer comparer = new BoxedRegistryItemComparer(); ArrayList.sort(comparer); However, the last line gives the compiler error: "Cannot convert from BoxedRegistryItemComparer to System.Collections.IComparer". I would appreciate it if someone could point out my mistake.

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• Saving jQuery UI Sortable's order to Backbone.js Collection

  - by VirtuosiMedia

  I have a Backbone.js collection that I would like to be able to sort using jQuery UI's Sortable. Nothing fancy, I just have a list that I would like to be able to sort. The problem is that I'm not sure how to get the current order of items after being sorted and communicate that to the collection. Sortable can serialize itself, but that won't give me the model data I need to give to the collection. Ideally, I'd like to be able to just get an array of the current order of the models in the collection and use the reset method for the collection, but I'm not sure how to get the current order. Please share any ideas or examples for getting an array with the current model order.

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• Postgresql: Implicit lock acquisition from foreign-key constraint evaluation

  - by fennec

  So, I'm being confused about foreign key constraint handling in Postgresql. (version 8.4.4, for what it's worth). We've got a couple of tables, mildly anonymized below: device: (id, blah, blah, blah, blah, blah x 50)… primary key on id whooooole bunch of other junk device_foo: (id, device_id, left, right) Foreign key (device_id) references device(id) on delete cascade; primary key on id btree index on 'left' and 'right' So I set out with two database windows to run some queries. db1> begin; lock table device in exclusive mode; db2> begin; update device_foo set left = left + 1; The db2 connection blocks. It seems odd to me that an update of the 'left' column on device_stuff should be affected by activity on the device table. But it is. In fact, if I go back to db1: db1> select * from device_stuff for update; *** deadlock occurs *** The pgsql log has the following: blah blah blah deadlock blah. CONTEXT: SQL statement "SELECT 1 FROM ONLY "public"."device" x WHERE "id" OPERATOR(pg_catalog.=) $1 FOR SHARE OF X: update device_foo set left = left + 1; I suppose I've got two issues: the first is that I don't understand the precise mechanism by which this sort of locking occurs. I have got a couple of useful queries to query pg_locks to see what sort of locks a statement invokes, but I haven't been able to observe this particular sort of locking when I run the update device_foo command in isolation. (Perhaps I'm doing something wrong, though.) I also can't find any documentation on the lock acquisition behavior of foreign-key constraint checks. All I have is a log message. Am I to infer from this that any change to a row will acquire an update lock on all the tables which it's foreign-keyed against? The second issue is that I'd like to find some way to make it not happen like that. I'm ending up with occasional deadlocks in the actual application. I'd like to be able to run big update statements that impact all rows on device_foo without acquiring a big lock on the device table. (There's a lot of access going on in the device table, and it's kind of an expensive lock to get.)

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• How to debug Ruby base methods in Netbeans ?

  - by Bragaadeesh

  Hi, I am able to debug my ruby program. At times, I would want to go inside the library methods and see what is happening. How to achieve it in Ruby. For example, [ 3, 1, 7, 0 ].sort i would want to go inside the sort method and see how that works lively. In Java+Eclipse this is possible, all I have to do is to attach the source of Foundation classes in Eclipse. Is it possible in Ruby with Netbeans as IDE? Thanks

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• lock file so that it cannot be deleted

  - by JoeCool

  I'm working with two independent c/c++ applications on Windows where one of them constantly updates an image on disk (from a webcam) and the other reads that image for processing. This works fine and dandy 99.99% of the time, but every once in a while the reader app is in the middle of reading the image when the writer deletes it to refresh it with a new one. The obvious solution to me seems to be to have the reader put some sort of a lock on the file so that the writer can see that it can't delete it and thus spin-lock on it until it can delete and update. Is there anyway to do this? Or is there another simple design pattern I can use to get the same sort of constant image refreshing between two programs? Thanks, -Robert

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• how to call different Win API based on Windows version?

  - by liuliu

  The specific problem is, the support of condition variable on Windows begins from Vista, for early version of Windows (Windows XP), I have a emulated condition variable code sort of solved the problem. However, I'd like to have the ability to call native condition variable API when the system supported and fallback to my version only on XP and earlier version. I tried to detect windows version with GetVersionInfo API, but it still gives me error on start time (cannot find API entry of InitializeConditionVariable sort of). I am not familiar with Windows programming, how do you solve the gentle fallback problem nicely?

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• Examples of how to visualize a versioning system?

  - by Alex Gilbert

  My shop is trying to formalize the release management process for an OSS product we maintain. It's a sort of a web development framework/CMS kind of thing, as in it's a product that other projects are built on top of. This makes clear communication about the versioning system especially critical for developers that are using the tool. I'm hoping to find some examples of how best to graph this system so we can communicate it better internally and with outside developers. I know there are lots of standards and best practices around versioning, so I'm hoping this extends to some sort of visual vocabulary as well. As one example, there is a nifty graph at http://en.wikipedia.org/wiki/Versioning#Software_Versioning_schemes. Are there any guides out there on how these sorts of things should be designed?

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• linq expression in vb.net

  - by Thurein

  Hi, Can any body translate the following c# code to vb. I have tried telarik code converter but I got problem at expression.call and it won't compile at all. private static IOrderedQueryable<T> OrderingHelper<T>(IQueryable<T> source, string propertyName, bool descending, bool anotherLevel) { ParameterExpression param = Expression.Parameter(typeof(T), string.Empty); MemberExpression property = Expression.PropertyOrField(param, propertyName); LambdaExpression sort = Expression.Lambda(property, param); MethodCallExpression call = Expression.Call( typeof(Queryable), (!anotherLevel ? "OrderBy" : "ThenBy") + (descending ? "Descending" : string.Empty), new[] { typeof(T), property.Type }, // error line source.Expression, Expression.Quote(sort)); return (IOrderedQueryable<T>)source.Provider.CreateQuery<T>(call); } thanks Thurein

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• How do I do automatic data serialization of data objects in Haskell

  - by Adam Gent

  One of the huge benefits in languages that have some sort of reflection/introspecition is that objects can be automatically constructed from a variety of sources. For example in Java I can use the same objects for persisting to a db (with Hibernate) serializing to XML (with JAXB) or serializing to JSON (json-lib). You can do the same in Ruby and Python also usually following some simple rules for properties or annotations for Java. Thus I don't need lots "Domain Transfer Objects". I can concentrate on the domain I am working in. It seems in very strict FP like Haskell and Ocaml this is not possible. Particularly Haskell. The only thing I have seen is doing some sort of preprocessing or meta-programming (ocaml). Is it just accepted that you have to do all the transformations from the bottom upwards? In other words you have to do lot of boring work to turn a data type in haskell into JSON/XML/DB Row object and back again into a data object.

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• Unchecked call to compareTo

  - by Dave Jarvis

  Background Create a Map that can be sorted by value. Problem The code executes as expected, but does not compile cleanly: http://pastebin.com/bWhbHQmT The syntax for passing Comparable as a generic parameter along to the Map.Entry<K, V> (where V must be Comparable?) -- so that the (Comparable) typecast shown in the warning can be dropped -- eludes me. Warning Compiler's cantankerous complaint: SortableValueMap.java:24: warning: [unchecked] unchecked call to compareTo(T) as a member of the raw type java.lang.Comparable return ((Comparable)entry1.getValue()).compareTo( entry2.getValue() ); Question How can the code be changed to compile without any warnings (without suppressing them while compiling with -Xlint:unchecked)? Related TreeMap sort by value How to sort a Map on the values in Java? http://paaloliver.wordpress.com/2006/01/24/sorting-maps-in-java/ Thank you!

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• Is it inmoral to put a captcha on a login form?

  - by azkotoki

  In a recent project I put a captcha test on a login form, in order to stop possible brute force attacks. The inmediate reaction of other coworkers was a request to remove it, saying that it was innapropiate for that purpose, and that it was quite exotic to see a captcha in that place. I've seen captcha images on signup, contact, password recovery forms, etc. So I personally don't see innapropiate to put a captcha also on a place like that. Well, it obviously burns down usability a little bit, but it's a matter of time and getting used to it. With the lack of a captcha test, one would have to put some sort of blacklist / account locking mechanism, which also has some drawbacks. Is it a good choice for you? Am I getting somewhat captcha-aholic and need some sort of group therapy? Thanks in advance.

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• Best data-structure to use for two ended sorted list

  - by fmark

  I need a collection data-structure that can do the following: Be sorted Allow me to quickly pop values off the front and back of the list Remain sorted after I insert a new value Allow a user-specified comparison function, as I will be storing tuples and want to sort on a particular value Thread-safety is not required Optionally allow efficient haskey() lookups (I'm happy to maintain a separate hash-table for this though) My thoughts at this stage are that I need a priority queue and a hash table, although I don't know if I can quickly pop values off both ends of a priority queue. I'm interested in performance for a moderate number of items (I would estimate less than 200,000). Another possibility is simply maintaining an OrderedDictionary and doing an insertion sort it every-time I add more data to it. Furthermore, are there any particular implementations in Python. I would really like to avoid writing this code myself.

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• Solr date range problem and specific date problem

  - by Hamid

  I index some data include date in solr but when search for specific date, i get some record (not all record) include some record in next day for example: http://localhost:8080/solr/select/?q=pubdate:[2010-03-25T00:00:00Z TO 2010-03-25T23:59:59Z]&start=0&rows=10&indent=on&sort=pubdate desc i have 625000 record in 2010-03-25 but above query result return 325412 that include 14 record from 2010-03-26. Also i try with below query, but not get right result http://localhost:8080/solr/select/?q=pubdate:"2010-03-25T00:00:00Z"&start=0&rows=10&indent=on&sort=pubdate desc How to get right result for specific date ??? Could you please help me? Thanks in advanced Hamid

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• Please help - sorting integers in structs

  - by maja k.

  I have a struct like this: struct db { string name,sur; int num; }; And declared an array of db structs: struct db a[10]; and every member of a[] is filled with a name, surname and a number but there can be the same number appearing multiple times. I need to sort the numbers, and print the results, i.e. sort by the num of each struct and the print the name, sur and the num in each line starting from the smallest num going down to the largest. I don't know how to do this, please help me.

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• Jenkins plugin for different types of slaves

  - by user1195996

  We have some tests that need to be run on multiple types of specific hardware. Its possible that these tests might pass on some pieces of hardware but fail on others, and we want to know where they work and where they fail. So, for certain tests, we would like to provide a list of hardware they need to be tested on. We'd like to put all the needed hardware in a pool that Jenkins has access to, and then have Jenkins run the right tests on the right hardware, depending on the hardware list that comes with the test. And of course we'd like to keep track of which test worked where. Is there a plugin for Jenkins to be able to handle this sort of thing? Has anyone else solved this sort of problem?

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• Sorting Arrays in Java

  - by jukababes

  How do i sort array elements into ascending order?

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• How to Command Query Responsibility Segregation (CQRS) with ASP.NET MVC?

  - by Jeffrey

  I have been reading about Command Query Responsibility Segregation (CQRS). I sort of wonder how would this work with ASP.NET MVC? I get the idea of CQRS conceptually it sounds nice and sure does introduce some complexities (event and messaging pattern) compared to the "normal/common" approach . Also the idea of CQRS sort of against the use of ORM in some ways. I am trying to think how I could use this pattern in the coming projects so if anyone has experience in combining CQRS with ASP.NET MVC and NHibernate please give some concrete examples to help me better understand CQRS and use with ASP.NET MVC. Thanks!

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• Performance statistics hooks

  - by tinny

  Lets be honest, most software that developers produce has quite modest performance requirements. E.g. Systems perhaps serving 100's of requests per second, if that. But lets assume for a moment (or even dream) that you where perhaps involved in the "next big thing" (whatever that means) and you wanted to put some sort of performance statistics logging in place to help you out when all those users come flying in. Performance statistics logging, how would you approach this requirement? Perhaps you would use some sort of generic framework for this? Or roll your own solution? What would you log? How granular? Or would you not even bother putting anything in place and rather deal with this issue when it actually became an issue? It would be really interesting to hear your thoughts on this topic.

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