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  • What's the best way to implement one-dimensional collision detection?

    - by cyclotis04
    I'm writing a piece of simulation software, and need an efficient way to test for collisions along a line. The simulation is of a train crossing several switches on a track. When a wheel comes within N inches of the switch, the switch turns on, then turns off when the wheel leaves. Since all wheels are the same size, and all switches are the same size, I can represent them as a single coordinate X along the track. Switch distances and wheel distances don't change in relation to each other, once set. This is a fairly trivial problem when done through brute force by placing the X coordinates in lists, and traversing them, but I need a way to do so efficiently, because it needs to be extremely accurate, even when the train is moving at high speeds. There's a ton of tutorials on 2D collision detection, but I'm not sure the best way to go about this unique 1D scenario.

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  • Finding relative libraries when using symlinks to ruby executables

    - by dgtized
    Imagine you have an executable foo.rb, with libraries bar.rb layed out in the following manner: <root>/bin/foo.rb <root>/lib/bar.rb In the header of foo.rb you place the following require to bring in functionality in bar.rb: require File.dirname(__FILE__)+"../lib/bar.rb" This works fine so long as all calls to foo.rb are direct. If you put as say $HOME/project, and symlink foo.rb into $HOME/usr/bin, then __FILE__ resolves to $HOME/usr/bin/foo.rb, and is thus unable to locate bar.rb in relation to the dirname for foo.rb. I realize that packaging systems such as rubygems fix this by creating a namespace to search for the library, and that it is also possible to adjust the load_path using $: to include $HOME/project/lib, but it seems as if a more simple solution should exist. Has anyone had experience with this problem and found a useful solution or recipe?

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  • Referencing the current jQuery object in a chain?

    - by Lance McNearney
    At DevDays in SF last year (before jQuery 1.4 was released), I thought they mentioned an upcoming feature in 1.4 that would allow you to reference the current jQuery object while in a chain. I've read through all of the 1.4 improvements and wasn't able to find it. Does anyone know how this can be done? Example Being able to access the current jQuery object would be helpful when working with methods that are in relation to the current object like .next(): // Current way var items = $(this).closest('tr'); items = items.add(items.next(':not([id])')); // Magical 1.4 way? Is there a "chain"-like object? var items = $(this).closest('tr') .add(chain.next(':not([id])'));

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  • Zend Framework Handle One to Many

    - by user192344
    I have 2 tables "user", "contact", the relation between two tables is one user has many contact Table member m_id name ------------ Table Contact c_id c_m_id value in zend model class, i do it in this way /* Member.php */ class Default_Model_DbTable_Member extends Zend_Db_Table_Abstract { protected $_name = 'member'; protected $_dependentTables = array('Default_Model_DbTable_Contact'); } /* Contact.php */ class Default_Model_DbTable_Contact extends Zend_Db_Table_Abstract { protected $_name = 'contact'; protected $_referenceMap = array( 'Member' => array( 'columns'=> array('c_id'), 'refTableClass'=> 'Default_Model_DbTable_Member', 'refColumns'=> array('c_m_id') ) ); /* IndexController.php */ class IndexController extends Zend_Controller_Action { public function indexAction() { $m= new Default_Model_DbTable_Member(); $row = $m->find(1); $data = $row->current(); $data = $data->findDependentRowset('Default_Model_DbTable_Contact'); print_r($data->toArray()); } } But i just get Invalid parameter number: no parameters were bound , my goal is to search a member detail record, and it also contains a array which store all contact info (i can use join method to do that, but i just want to try zend feature)

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  • PHP Get images from a UL list

    - by benjamin shrimpton
    I have a long UL list and each LI contains an image tag, dynamically generated from SLideshowPro Director. I need to get the widths of ALL the images inside the UL to use in a CSS width calculation. I have been able to get the image width for the first item, but not all. My PHP is pretty limited, but do I have to make this list into an ARRAY first to allow me to get all the widths? And how do i do that?? These images contain very long id's generated by the CMS, so reading through a directory is not possible, as the images in cache bare not relation to the file names that are output to the HTML page. It has to all be done from the content that's sent to the page. Or could I even use JQuery to do this??

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  • what's the key different between data management and data governance?

    - by Sid Xing
    i just read some articles about these two theories, and i thought they have the similar goal, but DG is more about process management by follow some best practice. So my 1st question is about the difference between DG & DM. I'm confused. There're so many concepts around data management. Data quality, data security, data governance, data profiling, data integration, master data management, metadata management.... It seems like neither of them is EXACTLY separated, they're together. My 2nd question, or ask for your suggestion to help me better understand the relation between these concepts. Appreciate your help.

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  • Hibernate inserting into join table

    - by Karl
    I got several entities. Two of them got a many-to-many relation. When I do a bigger operation on these entities it fails with this exception: org.hibernate.exception.ConstraintViolationException: could not insert collection rows: I execute the operation i a @Transactional context. I don't do any explicit flushing i my daos. The flush is triggered by a query. In the queue are 15 elements (all of the same structure). one of them always fails (but it's always a different one (I checked) and always at a different position). Does anybody have a hint for me for what I might do wrong? My Mapping: @ManyToMany(targetEntity = CategoryImpl.class) protected Set<Category> categories = new HashSet<Category>();

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  • [app-engine-java-groovy] One-to-Many relationship. Select objects from datastore.

    - by Olexandr
    Hi. I've omitted some code(package declarations, imports, other fields) for shortness. I have here simple One-to-Many relation. It worked fine till this moment. @PersistenceCapable(identityType = IdentityType.APPLICATION, detachable="true") class Restaurant implements Serializable { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) Key id @Persistent(mappedBy = "restaurant") List<RestaurantAddress> addresses = new ArrayList<RestaurantAddress>() } //-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= @PersistenceCapable(identityType = IdentityType.APPLICATION, detachable="true") class RestaurantAddress implements Serializable { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) Key id @Persistent Restaurant restaurant } Now i need to get(select) all the Restaurants from DB: def getRestaurantsToExport(final String dst, final int count) { String field = restaurantExportFields[dst] return transactionExecute() { PersistenceManager pm -> Query q = pm.newQuery(Restaurant.class) q.filter = "$field == null" q.setRange(0, count) return q.execute() } } But there are on problem - query gives me 12 restaurants(as in DB) but every Restaurant has 0 Address but in Datastore every Restaurant has minimum 2 addresses. Have anyone the same problem or knows the solution ?

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  • Equivalence Classes LISP

    - by orcik
    I need to write a program for equivalence classes and get this outputs... (equiv '((a b) (a c) (d e) (e f) (c g) (g h))) => ((a b c g h) (d e f)) (equiv '((a b) (c d) (e f) (f g) (a e))) => ((a b e f g) (c d)) Basically, A set is a list in which the order doesn't matter, but elements don't appear more than once. The function should accept a list of pairs (elements which are related according to some equivalence relation), and return a set of equivalence classes without using iteration or assignment statements (e.g. do, set!, etc.). However, set utilities such as set-intersection, set-union and a function which eliminates duplicates in a list and built-in functions union, intersection, and remove-duplicates are allowed. Thanks a lot!

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  • what else to do to establish many-to-many associations in Ruby on Rails? thanks!

    - by john
    Hi, I have two classes and I want to establish a many-to-many assications, here is the code: class Category < ActiveRecord::Base has_and_belongs_to_many :events has_and_belongs_to_many :tips end class Tip < ActiveRecord::Base has_and_belongs_to_many :categories However, I kept getting the following errors and I would appreciate it if some one could educate me what is going wrong: PGError: ERROR: relation "categories_tips" does not exist : SELECT "categories".id FROM "categories" INNER JOIN "categories_tips" ON "categories".id = "categories_tips".category_id WHERE ("categories_tips".tip_id = NULL ) the viewer part: 4: <%= text_field :tip, :title %></label></p> 5: 6: <p><label>Categories<br/> 7: <%= select_tag('categories[]', options_for_select(Category.find(:all).collect {|c| [c.name, c.id] }, @tip.category_ids), :multiple => true ) %></label></p> 8: 9: <p><label>Location<br/> 10: <%= text_field_with_auto_complete :tip, :abstract %></label></p>

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  • Accessing inter-schema tables and relations in hibernate

    - by nitesh
    There is a typical situation being faced where different tables are scattered through different schemas in Oracle database and they are related to each other (encompassing all different types of relations). How can they be represented in Hibernate using annotations as when a sessionfactory handle is created for one schema, tables in that schema can't access other related tables (foreign key relation to tables in other schema)? For a query like following, exception is thrown - "from table1 as model where model.table2Name.table2column = "+foo Exception comes as - org.hibernate.QueryException: could not resolve property: table2column of: com.test.table1 [from com.test.table1 as model where model.table2Name.table2column = 1] Here table1 and table2 are present in different schemas.

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  • Psycopg2 doesn't like table names that start with a lower case letter

    - by Count Boxer
    I am running ActiveState's ActivePython 2.6.5.12 and PostgreSQL 9.0 Beta 1 under Windows XP. If I create a table with an upper case first letter (i.e. Books), psycopg2 returns the "Programming Error: relation "books" does not exist" error message when I run the select statement: execute("SELECT * FROM Books"). The same error is returned if I run: execute("SELECT * FROM books"). However, if I change the table to a lower case first name (i.e. books), then either of the above statements works. Are tables name supposed to have a lower case first name? Is this a setting or a feature or a bug? Am I missing something obvious?

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  • Dowloading a bunch of files asynchronous wait till last finished

    - by Casper Broeren
    I'm trying to download a lot of files after downloading a sql statement must insert a record. I'm using System.Net.Client to download each file synchronously, still it could be done asynchronous. There's no relation or dependency between each download. At first I just tried to use WebClient.DownloadFileAsync but that shutted the program down and killed all the download processes/threads. Second I tried to create a wait routine something like this; while (processedFiles < totalFiles) Thread.Sleep(1000) This freezed everything. So could someone tell me which aproach to take to implement this Async?

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  • Jquery returns index -1 always

    - by jfreak53
    This is my index code that I use to return the buttons parent div's index: j('#optionform').index( j(this).parent() ) I'm trying to find out the DIV index of the button clicked, so I can remove the DIV. The HTML layout is like so: <form id="optionform" onsubmit="return false;"> <label><input type="checkbox" id="s_name" value="s_name"> Survey Name </label> <label><input type="checkbox" id="s_type" value="s_type"> Survey Type </label><br> Filter Results:<br> <div id="template" style="display: none;"> Column: <select id="fcolumn[]"> <option></option> <option value="s_name">Survey Name</option> <option value="s_type">Survey Type</option> </select><br> Filter Type: <select id="ftype[]"> <option></option> <option value="=">Equals</option> <option value="LIKE">Like</option> </select><br> Filter content: <input type="text" id="fcontent[]"><br> <img src="images/add.png" width="32px" onclick="addTemp(); return false;"> <img src="images/delete.png" width="32px" onclick="alert(j(this).attr('src')); remTemp(j('#optionform').index( j(this).parent() )); return false;"> </div> <div class="template" style="display: block;"> Column: <select id="fcolumn[]"> <option></option> <option value="s_name">Survey Name</option> <option value="s_type">Survey Type</option> </select><br> Filter Type: <select id="ftype[]"> <option></option> <option value="=">Equals</option> <option value="LIKE">Like</option> </select><br> Filter content: <input type="text" id="fcontent[]"><br> <img src="images/add.png" width="32px" onclick="addTemp(); return false;"> <img src="images/delete.png" width="32px" onclick="alert(j(this).attr('src')); remTemp(j('#optionform').index( j(this).parent() )); return false;"> </div> <div class="template" style="display: block;"> Column: <select id="fcolumn[]"> <option></option> <option value="s_name">Survey Name</option> <option value="s_type">Survey Type</option> </select><br> Filter Type: <select id="ftype[]"> <option></option> <option value="=">Equals</option> <option value="LIKE">Like</option> </select><br> Filter content: <input type="text" id="fcontent[]"><br> <img src="images/add.png" width="32px" onclick="addTemp(); return false;"> <img src="images/delete.png" width="32px" onclick="alert(j(this).attr('src')); remTemp(j('#optionform').index( j(this).parent() )); return false;"> </div> </form> But it always returns -1 in the index.

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  • doubt in Exceptions

    - by Ajay Singh
    class MyException extends Exception { MyException() {} MyException(String msg) { super(msg);} } public class NewException { static void f() throws MyException { System.out.println("throwing exception from f()"); throw new ClassCastException(); } static void g() throws MyException { System.out.println("throwing exception from g()"); throw new MyException("parametrized "); } public static void main(String ...strings ) { try { f(); } catch(MyException e) { e.printStackTrace(System.out); } try { g(); } catch(MyException e) { e.printStackTrace(System.out); } } } In the function f() iam specifying that "MyException " exception will be thrown and actually iam throwing some other exception which has no relation with MyException but still the compiler does not report any complain.Why is it so??

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  • PLINQO Not Naming Entities Correctly

    - by Clever Human
    I have my CSP file set up to use TableNaming and EntityNaming as Singular: <TableNaming>Singular</TableNaming> <EntityNaming>Singular</EntityNaming> Yet the generated entities are plural. For instance, I have a table called Companies. The generated name is "Companies" I expected "Company" (like LinqToSql did -- I am upgrading a project.) I have a table named EntityStorageItems (no relation to these entities.) The generated name is "EntityStorageItems" I expected the entity name to be "EntityStorageItem" IOW, it is creating plural names. And I need them to be singular (to work with existing code.) Am I doing something wrong?

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  • How to return relationships in a custom un-typed dataservice provider

    - by monkey_p
    I have a custom .Net DataService and can't figure out how to return the data for relationships. The data base has 2 tables (Customer, Address). A Customer can have multiple addresses, but each address can only have on customer. I'm using Dictionary<string,object> as my data type. My question, for the following 2 urls how do i return the data. http://localhost/DataService/Customer(1)/Address http://localhost/DataService/Address(1)/Customer For the none relational queries I return a List<Dictionary<string,object>> So I imagined for the relation I should just populate the element with a either a Dictionary<string,object> for the single ones and a List<Dictionary<string,object>> for many relationships. But this just gives me a NullRefferenceException So what am I doing wrong?

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  • using setSfGuardUser() to save the current user in the model

    - by user334017
    My application makes use of the sfGuardUser plugin. One of my tables has a relation onto the sf_guard_user table so there is a corresponding setSfGuardUser() function in the base model. From Actions.class.php, I am attempting to set the current user into the object using this function, (Which I then save in the database). my attempt: ->setSfGuardUser($this->getUser()); //called from inside Actions.class.php this throws an error: Couldn't call Doctrine_Core::set(), second argument should be an instance of Doctrine_Record or Doctrine_Null when setting one-to-one references. ...# at Doctrine_Record->coreSetRelated('sfGuardUser', object('myUser')) Which makes me think that getUser() is not returning a sfGuardUser object, though I don't know how to check this. Can anyone offer any insight?

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  • Help with a algorithm in linq to resolve a query

    - by Deumber
    I have been some time thinking how to resolve this problem, but out of ideas i prefer expose it for help. I have 2 tables (linq to sql) A and B, A have a many relation with B, so A have a property EntitySet of B A have the following properties: CreateDate (Datetime) ModificateDate (Datetime) Bs (EntitySet<B>) B have the following properties: CreateDate (Datetime) ModificateDate (Datetime) All that i want is return a ordered collection of A by the Max date between : A.CreateDate, A.ModificateDate, The Max B.CreateDate of all B in A The Max B.ModificateDate of all B in A if i someone need a little example, just ask for it.

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  • What is a good solution to link different tables in Hibernate based on some field value?

    - by serg555
    I have article table and several user tables a_user, b_user, ... with exactly the same structure (but different data). I can't change anything in *_user tables except their table name prefix but can change everything else (user tables contain only user information, there is nothing about article or user_type in them). I need to link article to a user (many-to-one), but user table name is defined by user_type field. For example Article table record: ... user_id="5" user_type="a" means that it is linked to a user with id=5 from a_user table (id 5 is not unique in users scope, each user table can have its id 5). Any suggestions how to handle this situation? How can I map this relation in Hibernate (xml mapping, no annotations) so it will automatically pick up correct user for an article during select/update? How should I map user tables (one or multiple classes?)? I would need to run some queries like this: from Article a where a.userType=:type and a.user.name=:name Thanks.

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  • SQL - Dervied Foreign Key - Possible?

    - by Chad
    I'm just curious if this is possible, specifically in SQL CE (Express) with support in .NET's Entity Framework: Table1 (primary) -nvarchar(2000) url -... Table2 (with foreign key) -nvarchar(2000) domain -... foreign key on Table2.domain references Table1.url such that Table.url contains Table2.domain e.g. Table1: http://www.google.com/blah/blah http://www.cnn.com/blah/ http://www.google.com/foo Table2: google.com cnn.com Is it possible for this to be scripted and enforced by SQL CE (let alone any relation database) and, if so, can .NET's Entity Framework automatically support this if I import my database into a model?

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  • ManyToManyField error when having recursive structure. How to solve it?

    - by luc
    Hello, I have the following table in the model with a recursive structure (a page can have children pages) class DynamicPage(models.Model): name = models.CharField("Titre",max_length=200) parent = models.ForeignKey('self',null=True,blank=True) I want to create another table with manytomany relation with this one: class UserMessage(models.Model): name = models.CharField("Nom", max_length=100) page = models.ManyToManyField(DynamicPage) The generated SQL creates the following constraint: ALTER TABLE `website_dynamicpage` ADD CONSTRAINT `parent_id_refs_id_29c58e1b` FOREIGN KEY (`parent_id`) REFERENCES `website_dynamicpage` (`id`); I would like to have the ManyToMany with the page itself (the id) and not with the parent field. How to modify the model to make the constraint using the id and not the parent? Thanks in advance

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  • I can't understand GroupJoin where i will need it in database relationships.

    - by Freshblood
    Hello Everybody I am thinking 5-6 hours to understand something about GroupJoin. I am talking about query with linq for Database tables.I understand what Join and GroupJoin does but I really couldn't understand where i will need it.I feel that Join does all what i will need but if there is something which Join can't without GroupJoin so i feel that situation is meaningless or useless. For example: Persons table in relation with Phones and Phones table hold foreign keys of Persons and one person can have one more phone number.If we want to brings all persons who has phone numbers and who hasn't too so we will need GroupJOin but what for we will need this query ? Can u give me good reason , example or explenation for using GroupJoin ?

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  • NHibernate SchemaUpdate adding existing foreign keys again?

    - by afsharm
    I'm using SchemaUpdate to synchronize my hbms with existing database. Database has recently created based on hbms and is completely up-to-date. But SchemaUpdate generates all foreign key constraints again. For example suppose you have Student and Teacher. Student has association to Teacher with name ArtTeacher. ArtTeacher is a foreign key from Student to Teacher. Suppose database is up-to-date and currently holde Student, Teacher and their foreign key relation. So HBM and Database are equivalent. Know SchemaUpdate must not do anything but when I see its generated scripts, it re-produce that foreign key again. Why this happens? Is there any way to avoid it?

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  • How to implement message passing in GNUradio?

    - by xuandl
    I need to implement message passing, my idea is to make some sort of message source (I inherit from public gr_sync_block) that works as a controller for another block (it has to send a message each 6 minutes). I read that is necessary to inherit from gnuradio::block -and by the way, installing grextras is mandatory-. In the .h file I added the #include and inherited from block"class JDFM_API jdfm_control : public gr_sync_block, public gnuradio::block". I know that I have redefine some things like the gnuradio::block constructor but I dont know what msg_signature is, I also don't get the relation between block's parameters and work parameter, the last thing that I am not sure is if I still can use gnuradio-companion if I create a block like this. I haven't been able to find a simple example of messages implementation. If anyone can guide me or show me an example, it would be awesome. Thanks in advance.

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