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  • Rails Counter Cache and its implementation

    - by Ishu
    Hello All, I am trying to get hold of rails counter cache feature but not able to grasp it completely. Let's say that We have 3 models A B C A belongs to B or C depending upon a field key_type and key_id. key_type tells whether A belongs to B or C so if key_type="B" then the record belongs to B otherwise it belongs to C. In my model a.rb, I have defined following associations: belongs_to :b, :counter_cache => true, :foreign_key => "key_id" belongs_to :c, :counter_cache => true, :foreign_key => "key_id" and in b and c model files has_many :as , :conditions => {:key_type => "B"} has_many :as , :conditions => {:key_type => "C"} Both B and C Models have a column as as_count The problem is every time an object of a is created count is increased in the both the models b and c. Any help is appreciated. Initially i thought that this may work: belongs_to :b, :counter_cache => true, :foreign_key => "key_id", :conditions => {:key_type => "B"} belongs_to :c, :counter_cache => true, :foreign_key => "key_id", :conditions => {:key_type => "C"} But this does not help. Thanks

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  • ActiveRecord Validations for Models with has_many, belongs_to associations and STI

    - by keruilin
    I have four models: User Award Badge GameWeek The associations are as follows: User has many awards. Award belongs to user. Badge has many awards. Award belongs to badge. User has many game_weeks. GameWeek belongs to user. GameWeek has many awards. Award belongs to game_week. Thus, user_id, badge_id and game_week_id are foreign keys in awards table. Badge implements an STI model. Let's just say it has the following subclasses: BadgeA and BadgeB. Some rules to note: The game_week_id fk can be nil for BadgeA, but can't be nil for BadgeB. Here are my questions: For BadgeA, how do I write a validation that it can only be awarded one time? That is, the user can't have more than one -- ever. For BadgeB, how do I write a validation that it can only be awarded one time per game week?

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  • What's the correct terminology for something that isn't quite classification nor regression?

    - by TC
    Let's say that I have a problem that is basicly classification. That is, given some input and a number of possible output classes, find the correct class for the given input. Neural networks and decision trees are some of the algorithms that may be used to solve such problems. These algorithms typically only emit a single result however: the resulting classification. Now what if I weren't only interested in one classification, but in the posterior probabilities that the input belongs to each of the classes. I.E., instead of the answer "This input belongs in class A", I want the answer "This input belongs to class A with 80%, class B with 15% and class C with 5%". My question is not on how to obtain these posterior probabilities, but rather on the correct terminology to describe the process of finding them. You could call it regression, since we are now trying to estimate a number of real valued numbers, but I am not quite sure if that's right. I feel it's not exactly classification either, it's something in between the two. Is there a word that describes the process of finding the class conditional posterior probabilities that some input belongs in each of the possible output classes? P.S. I'm not exactly sure if this question is enough of a programming question, but since it's about machine learning and machine learning generally involves a decent amount of programming, let's give it a shot.

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  • How to add a hierarchical tag in an XML file though XSL?

    - by Hetal
    Hello, I am facing a problem in XML transformation. Sorry if the question is asked before. The XML tag hierarchy is as follows: //This tag contains the header data (Example:Pick Slip Number) Then the Detail lines are printed. The detail lines are printed. This detail line belongs to the previous Pick Slip Number. The detail lines are printed. This detail line belongs to the previous Pick Slip Number. My requirement is to: //This tag contains the header data (Example:Pick Slip Number) Then the Detail lines are printed. The detail lines are printed. This detail line belongs to the previous Pick Slip Number. The detail lines are printed. This detail line belongs to the previous Pick Slip Number. My requirement is to print the Pick Slip Number at every page on the header. Since there is no parent tag for and , I face the problem while printing. I am trying to serach something in XML transformation. But I dont know how to transform the XML tag hierarchy. I have attached the XML file for the reference. Thanks..

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  • Mounting GlusterFS share under www-data user

    - by Roman Newaza
    Problem: After directory is auto-mounted, Web Server has no write permissions to it. Question: How to auto-mount GlusterFS endpoint via /etc/fstab so that mount point belongs to www-data after it's mounted? For now, the mount point belongs to www-data, but after mounting it turns to root. # /etc/fstab foo.com:/st /st glusterfs defaults 0 0 Seams like I cannot define user / group as mount options for GlusterFS, at least I don't see it when man glusterfs. Thanks!

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  • How can I identify a mystery tray icon in Windows 7?

    - by Mark
    A new icon has appeared in my tray in Windows 7 recently - a black square with a white A in it: It doesn't have any tooltip or right-click context menu so I haven't been able to identify which process it belongs to. I tried using the "Find Window's Process" tool in Process Explorer but that won't identify individual tray icons. Short of killing processes until it disappears, is there a good way to identify which process this icon belongs to?

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  • Why does the token returned by LogonUser() in Win x64 not belong to LOCAL group?

    - by edwinbs
    Hi, I have a piece of code that calls LogonUser() followed by CreateProcessAsUser(). In Win32, the resulting process belongs to a user (say, TESTDOMAIN\user1) who belongs to the LOCAL group. However, in x64, the process owner does not belong to LOCAL. The owner still belongs to all other groups (Authenticated Users, Everyone, etc.) Does anyone know if this is a documented behavior change? Or am I supposed to put some special flag in x64 when calling LogonUser()? Thanks.

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  • Best approach to update a control after an Ajax request?

    - by Cuga
    I have a webpage that fires off an Ajax request which stores some data to a database and I want to update the webpage so that the user can see their changes have been submitted. There are at least 3 ways I can think of accomplishing this: Immediately update the webpage with plain JavaScript by grabbing the contents of the user's inputted text and immediately inserting it where it belongs. Have the ajax call return the stored text as the response, grab the response, and then insert this text where it belongs on the page using JavaScript Have the ajax call return a flag (say, true for successful db write, false otherwise), and if the flag is true, use JavaScript to grab the user's contents from the input control and insert it where it belongs elsewhere on the page Or another method not mentioned...? I don't mean this to be subjective, I just don't know which would be the best method to apply. My instinct tells me to go with the third item (return a flag, then update the field). Is this the best way? Thanks

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  • Actor and Sprite, who should own these properties?

    - by Gerardo Marset
    I'm writing sort of a 2D game engine for making the process of creating games easier. It has two classes, Actor and Sprite. Actor is used for interactive elements (the player, enemies, bullets, a menu, an invisible instance that controls score, etc) and Sprite is used for animated (or not) images with transparency (or not). The actor may have an assigned sprite that represents it on the screen, which may change during the game. E.g. in a top-down action game you may have an actor with a sprite of a little guy that changes when attacking, walking, and facing different directions, etc. Currently the actor has x and y properties (its coordinates in the screen), while the sprite has an index property (the number of the frame currently being shown by the sprite). Since the sprite doesn't know which actor it belongs to (or if it belongs to an actor at all), the actor must pass its x and y coordinates when drawing the sprite. Also, since a actors may reset its sprite each frame (and usually do), the sprite's index property must be passed from the old to the new sprite like so (pseudocode): function change_sprite(new_sprite) old_index = my.sprite.index my.sprite = new_sprite() my.sprite.index = old_index % my.sprite.frames end I always thought this was kind of cumbersome, but it never was a big problem. Now I decided to add support for more properties. Namely a property to draw the sprite rotated, a property to draw it flipped, it a property draw it stretched, etc. These should probably belong to the sprite and not the actor, but if they do, the actor would have to pass them from the old to the new sprite each time it changes... On the other hand, if they belonged to the actor, the actor would have to pass each property to the sprite when drawing it (since the sprite doesn't know which actor it belongs to, and it shouldn't, since sprites aren't just meant to be used by actors, really). Another option I thought of would be having an extra class that owns all these properties (plus index, x and y) and links an actor with a sprite, but that doesn't come without drawbacks. So, what should I do with all these properties? Thanks!

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  • What is the use of Association, Aggregation and Composition (Encapsulation) in Classes

    - by SahilMahajanMj
    I have gone through lots of theories about what is encapsulation and the three techniques of implementing it, which are Association, Aggregation and Composition. What i found is, Encapsulation Encapsulation is the technique of making the fields in a class private and providing access to the fields via public methods. If a field is declared private, it cannot be accessed by anyone outside the class, thereby hiding the fields within the class. For this reason, encapsulation is also referred to as data hiding. Encapsulation can be described as a protective barrier that prevents the code and data being randomly accessed by other code defined outside the class. Access to the data and code is tightly controlled by an interface. The main benefit of encapsulation is the ability to modify our implemented code without breaking the code of others who use our code. With this feature Encapsulation gives maintainability, flexibility and extensibility to our code. Association Association is a relationship where all object have their own lifecycle and there is no owner. Let’s take an example of Teacher and Student. Multiple students can associate with single teacher and single student can associate with multiple teachers but there is no ownership between the objects and both have their own lifecycle. Both can create and delete independently. Aggregation Aggregation is a specialize form of Association where all object have their own lifecycle but there is ownership and child object can not belongs to another parent object. Let’s take an example of Department and teacher. A single teacher can not belongs to multiple departments, but if we delete the department teacher object will not destroy. We can think about “has-a” relationship. Composition Composition is again specialize form of Aggregation and we can call this as a “death” relationship. It is a strong type of Aggregation. Child object dose not have their lifecycle and if parent object deletes all child object will also be deleted. Let’s take again an example of relationship between House and rooms. House can contain multiple rooms there is no independent life of room and any room can not belongs to two different house if we delete the house room will automatically delete. The question is: Now these all are real world examples. I am looking for some description about how to use these techniques in actual class code. I mean what is the point for using three different techniques for encapsulation, How these techniques could be implemented and How to choose which technique is applicable at time.

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  • User script at logout

    - by GUI Junkie
    The problem: I'm sharing a directory with my wife. I've placed us both in a 'shared' group and the directory belongs to the 'shared' group as well. Whenever one of us creates a file, this file belongs to user:user, instead of user:shared... The solution: I can do sudo chown, but my wife can't. So, I want to run a script when I logout of the session. If I understand correctly, the startup scripts go in /etc/init.d/ and the runlevel scripts go /etc/rc0.d/ where 0 is the runlevel (0-6). Do the runlevel scripts execute only on exit/logout? Do these depend on the user, that is, I'd like to run it only for my user (not so important in this case, mind)? Should I place the script somewhere else? Also, I imagine that the script will be run by root, so there's no need for sudo within the script, is that correct?

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  • OOP PHP make separate classes or one

    - by user2956219
    I'm studying OOP PHP and working on a small personal project but I have hard time grasping some concepts. Let's say I have a list of items, each item belongs to subcategory, and each subcategory belongs to category. So should I make separate classes for category (with methods to list all categories, add new category, delete category), class for subcategories and class for items? Or should I make creating, listing and deleting categories as methods for item class? Both category and subcategory are very simple and basically consist of ID, Name and parentID (for subcategory).

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  • Are same IP address with different submask unique?

    - by xEnOn
    In a same block of IPv4 addresses, can there be same IPs with different submasks? For example, can I have this: 180.70.65.140/26 180.70.65.140/25 180.70.65.140/24 All the 3 addresses above have the same numbers but different subnet mask. Are all the 3 addresses distinct of their own? In other words, 180.70.65.140/25 belongs to User A, 180.70.65.140/25 belongs to User B and 180.70.65.140/24 belongs to User C? After applying the submask, their network addresses look like this: 180.70.65.140/26 --> 180.70.65.128/26 180.70.65.140/25 --> 180.70.65.128/25 180.70.65.140/24 --> 180.70.65.0/24 If the addresses are recognised uniquely, how is it so? How would each of the these addresses being recognised to be unique? I am thinking like once I have 180.70.65.140/26, I can't reuse the same numbers of 180.70.65.140 again but since classless is meant to increase the number of IP addresses, it would do much if I can't reuse.

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  • Microsoft.Office.Interop.Excel.ListObject vs Microsoft.Office.Tools.Excel.ListObject

    - by Kavita A
    I need to access the Selected Event of all the listobjects in all the worksheets of my workbook but when I access worksheet.listobject, that object apparently belongs to Microsoft.Office.Interop.Excel.ListObject and so doesn't have any events where as the table list object belongs to Microsoft.Office.Tools.Excel.ListObject. And I read that Microsoft.Office.Tools.Excel.ListObject.InnerObject = Microsoft.Office.Interop.Excel.ListObject but i don't know how to use it. Pls Help Thanks, Kavita

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  • Kohana ORM get one record in many-to-many relationship

    - by booze2go
    Hi Guys, I've got two tables (items / tags). Item has and belongs to many tags - tag has and belongs to many items. It's no problem for me to fetch all related tags like: $item = ORM::factory('item', 4); foreach($item->tags as $tag){....} But how can i fetch only one... and maybe a specific one? Thanks in advance!

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  • Test if a number is fibonacci

    - by VaioIsBorn
    I know how to make the list of the Fibonacci numbers, but i don't know how can i test if a given number belongs to the fibonacci list - one way that comes in mind is generate the list of fib. numbers up to that number and see if it belongs to the array, but there's got to be another, simpler and faster method. Any ideas ?

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  • Algorithm reductions

    - by Marthin
    If I have a algorithm A that i have proven belongs to P can this algorithm also belong to the NPC class or is it strictly P? What about NP? P Belongs to NP right? Thx for any help! /Marthin

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  • CakePHP Multiple Nested Joins

    - by Paul
    I have an App in which several of the models are linked by hasMany/belongsTo associations. So for instance, A hasMany B, B hasMany C, C hasMany D, and D hasMany E. Also, E belongs to D, D belongs to C, C belongs to B, and B belongs to A. Using the Containable behavior has been great for controlling the amount of information comes back with each query, but I seem to be having a problem when trying to get data from table A while using a condition that involves table D. For instance, here is an example of my 'A' model: class A extends AppModel { var $name = 'A'; var $hasMany = array( 'B' => array('dependent' => true) ); function findDependentOnE($condition) { return $this->find('all', array( 'contain' => array( 'B' => array( 'C' => array( 'D' => array( 'E' => array( 'conditions' => array( 'E.myfield' => $some_value ) ) ) ) ) ) )); } } This still gives me back all the records in 'A', and if it's related 'E' records don't satisfy the condition, then I just get this: Array( [0] => array( [A] => array( [field1] => // stuff [field2] => // more stuff // ...etc ), [B] => array( [field1] => // stuff [field2] => // more stuff // ...etc ), [C] => array( [field1] => // stuff [field2] => // more stuff // ...etc ), [D] => array( [field1] => // stuff [field2] => // more stuff // ...etc ), [E] => array( // empty if 'E.myfield' != $some_value' ) ), [1] => array( // ...etc ) ) When If 'E.myfield' != $some_value, I don't want the record returned at all. I hope this expresses my problem clearly enough... Basically, I want the following query, but in a database-agnostic/CakePHP-y kind of way: SELECT * FROM A INNER JOIN (B INNER JOIN (C INNER JOIN (D INNER JOIN E ON D.id=E.d_id) ON C.id=D.c_id) ON B.id=C.b_id) ON A.id=B.a_id WHERE E.myfield = $some_value

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  • Is information a subset of data?

    - by Jason Baker
    I apologize as I don't know whether this is more of a math question that belongs on mathoverflow or if it's a computer science question that belongs here. That said, I believe I understand the fundamental difference between data, information, and knowledge. My understanding is that information carries both data and meaning. One thing that I'm not clear on is whether information is data. Is information considered a special kind of data, or is it something completely different?

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  • Weakly connected tree

    - by wow_22
    hello I have an algorithmic problem using a weakly connected tree T where w(T)=sum(w(e)) for each edge e,by w i declare weight and i have to prove that we can use prim and Kruskal algorithm while w(T)=max{w(e)} maximum between any edge e belongs at T (I proved that) but i have also to prove the same for w(T)=?(w(e)) while ? states product of all edges belongs at T i tried a lot to prove it but i did not came up with a result that proving or disapproving the use of prim ,kruskal any help will be more than appreciated thanks

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  • Add a datatable to a data set

    - by Jibu P C_Adoor
    Hii... I have a data table 'dt1' that is belongs to 'ds1'. I have created another instance of dataset 'ds2' and try to add the datatable 'dt1' to 'ds2'. Now i got one exception 'DataTable already belongs to another data set'. Is there any reliable way to add the dt1 to ds2?

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  • Rails Association Question...

    - by keruilin
    I have three models: User, RaceWeek, Race # Current associations: User has_many race_weeks; RaceWeek belongs to user; RaceWeek has many races; Race belongs to RaceWeek # So the user_id is a foreign key in RaceWeek and race_week_id is a foreign key in Race. # fastest_time is an attribute of the Race model. # QUESTION: What's the optimal way to retrieve a list of users who have the top X fastest race times?

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  • Changes to multiple entities within a single transaction

    - by Nati
    Hy, I am trying to make changes to multiple entities within a single transaction in app engine platform. As I understand in order to succeed doing so, App Engine needs to know in advance which entities will be updated together, so it knows to store them in a way that supports transactions. And therefore, user must declare that an entity belongs to the same entity group as another entity when you create the entity. How do I declare that one entity belongs to another entity group in creation time? Thanks, Nati

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  • Django: Complex filter parameters or...?

    - by minder
    This question is connected to my other question but I changed the logic a bit. I have models like this: from django.contrib.auth.models import Group class Category(models.Model): (...) editors = ForeignKey(Group) class Entry(models.Model): (...) category = ForeignKey(Category) Now let's say User logs into admin panel and wants to change an Entry. How do I limit the list of Entries only to those, he has the right to edit? I mean: How can I list only those Entries which are assigned to a Category that in its "editors" field has one of the groups the User belongs to? What if User belongs to several groups? I still need to show all relevant Entries. I tried experimenting with changelist_view() and queryset() methods but this problem is a bit too complex for me. I'm also wondering if granular-permissions could help me with the task, but for now I have no clue. I came up only with this: First I get the list of all Groups the User belongs to. Then for each Group I get all connected Categories and then for each Category I get all Entries that belong to these Categories. Unfortunately I have no idea how to stitch everything together as filter() parameters to produce a nice single QuerySet.

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  • Running a Model::find in for loop in cakephp v1.3

    - by Gaurav Sharma
    Hi all, How can I achieve the following result in cakephp: In my application a Topic is related to category, category is related to city and city is finally related to state in other words: topic belongs to category, category belongs to city , city belongs to state.. Now in the Topic controller's index action I want to find out all the topics and it's city and state. How can I do this. I can easily do this using a custom query ($this-Model-query() function ) but then I will be facing pagination difficulties. I tried doing like this function index() { $this->Topic->recursive = 0; $topics = $this->paginate(); for($i=0; $i<count($topics);$i++) { $topics[$i]['City'] = $this->Topic->Category->City->find('all', array('conditions' => array('City.id' => $topics[$i]['Category']['city_id']))); } $this->set(compact('messages')); } The method that I have adopted is not a good one (running query in a loop) Using the recursive property and setting it to highest value (2) will degrade performance and is not going to yield me state information. How shall I solve this ? Please help Thanks

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