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  • How to structure a Genetic Algorithm class hierarchy?

    - by MahlerFive
    I'm doing some work with Genetic Algorithms and want to write my own GA classes. Since a GA can have different ways of doing selection, mutation, cross-over, generating an initial population, calculating fitness, and terminating the algorithm, I need a way to plug in different combinations of these. My initial approach was to have an abstract class that had all of these methods defined as pure virtual, and any concrete class would have to implement them. If I want to try out two GAs that are the same but with different cross-over methods for example, I would have to make an abstract class that inherits from GeneticAlgorithm and implements all the methods except the cross-over method, then two concrete classes that inherit from this class and only implement the cross-over method. The downside to this is that every time I want to swap out a method or two to try out something new I have to make one or more new classes. Is there another approach that might apply better to this problem?

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  • SQL Server: pulling and updating local data

    - by SDReyes
    Hi guys, I have two SQL Server 2008 databases called Anna and Bob. Bob has to pull and transform data from Anna to keep updated his tables. Ideally Bob will be always synchronized with Anna, but some delay would be acceptable. What is the best way to do this? Thanks in advance.

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  • Reuse nib's across multiple UIViewControllers

    - by colm
    I've created some custom UITableViewCells in a nib file and would like to use that across multiple UIViewControllers. Can anyone tell me the best practice way to do that? My limited knowledge around loading nibs seems to suggest that you have to specify a single owner class in Interface Builder. Thanks.

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  • Proper way to set class variables

    - by ensnare
    I'm writing a class to insert users into a database, and before I get too far in, I just want to make sure that my OO approach is clean: class User(object): def setName(self,name): #Do sanity checks on name self._name = name def setPassword(self,password): #Check password length > 6 characters #Encrypt to md5 self._password = password def commit(self): #Commit to database >>u = User() >>u.setName('Jason Martinez') >>u.setPassword('linebreak') >>u.commit() Is this the right approach? Should I declare class variables up top? Should I use a _ in front of all the class variables to make them private? Thanks for helping out.

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  • Daylight saving time - do and don'ts

    - by Oded
    I am hoping to make this question and the answers to it the definitive guide to dealing with daylight saving time, in particular for dealing with the actual change overs. Many systems are dependent on keeping accurate time, the problem is with changes to time due to daylight savings - moving the clock forward or backwards. For instance, one has business rules in an order taking system that depend on the time of the order - if the clock changes, the rules might not be as clear. How should the time of the order be persisted? There is of course an endless number of scenarios - this one is simply an illustrative one. How have you dealt with the daylight saving issue? What assumptions are part of your solution? (looking for context here) As important, if not more so: What did you try that did not work? Why did it not work? I would be interested in programming, OS, data persistence and other pertinent aspects of the issue. General answers are great, but I would also like to see details especially if they are only available on one platform.

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  • algorithm diagram

    - by tunl
    This is the max searching algorithm diagram: So, I wonder how can draw diagram for Recursion in HaNoi Tower program: package tunl; public class TowersApp { static int n = 3; public static void main(String[] args) { TowersApp.doTowers(3, 'A', 'B', 'C'); } public static void doTowers(int n, char from, char inter, char to) { if (n == 1) { System.out.println("disk 1 from "+ from + " to " + to); } else { doTowers(n-1, from, to, inter); System.out.println("disk " + n + " from " + from + " to " + to); doTowers(n-1, inter, from, to); } } } I can't draw it. Anyone can help me !!!

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  • Suggest a Game Idea for my 3D World

    - by mrlinx
    Been creating a 3D complete world in OpenGL. For now, it features navigation like Google Earth, making possible the zooming from outter space to meter like level. My question is: How do you suggest I make this a fun and interesting game? My initial tought was to have a kind of moon lander where the user simply navigated the lander around the world. Anything better to suggest?

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  • 3rd party data - Store in Data Warehouse or Primary database?

    - by brydgesk
    This is mostly a data warehouse philosophy question. My project involves an Oracle forms application, and a Teradata Data Warehouse for reporting and ad-hoc purposes. In addition to the primary data created by the users of our application, we also require data from various other sources. Currently, this 3rd party data comes via FTPd flat files directly to our Data Warehouse. To access the data, our users must use a series of custom BusinessObjects reports. My question is, would it make more sense for this data to be sent to our source Oracle system instead? Is it ever appropriate for a Data Warehouse to be the point of origin for users to access raw data? In short, is it more important that the operational database contain only the data created by your project, or that the data warehouse remain dedicated solely to reporting and analysis?

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  • How is jQuery so fast?

    - by ClarkeyBoy
    Hey, I have a rather large application which, on the admin frontend, takes a few seconds to load a page because of all the pageviews that it has to load into objects before displaying anything. Its a bit complex to explain how the system works, but a few of my other questions explains the system in great detail. The main difference between what they say and the current system is that the customer frontend no longer loads all the pageviews into objects when a customer first views the page - it simply adds the pageview to the database and creates an object in an unsynchronised list... to put it simply, when a customer views a page it no longer loads all the pageviews into objects; but the admin frontend still does. I have been working on some admin tools on the customer frontend recently, so if an administrator clicks the description of an item in the catalogue then the right hand column will display statistics and available actions for the selected item. To do this the page which gets loaded (through $('action-container').load(bla bla bla);) into the right hand column has to loop through ALL the pageviews - this ultimately means that ALL the pageviews are loaded into objects if they haven't been already. For some reason this loads really REALLY fast. The difference in speed is only like a second on my dev site, but the live site has thousands of pageviews so the difference is quite big... So my question is: why is it that the admin frontend loads so slowly while using $(bla).load(bla); is so fast? I mean whatever method jQuery uses, can't browsers use this method too and load pages super-fast? Obviously not as someone would've done that by now - but I am interested to know just why the difference is so big... is it just my system or is there a major difference in speed between the browser getting a page and jQuery getting a page? Do other people experience the same kind of differences? Thanks in advance, Regards, Richard

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  • Save data in bulk.

    - by Muhammad Kashif Nadeem
    I have a window having multiple tabs. Each tab having different grids. I want to save all changes on any tab on any grid in bulk. I mean I have one save button which will save all changes in any grid on any tab. I think DataTables will work fine here. Can you suggest me that it is good to use DataTables to ADD/Edit data and save data in bulk using these DataTables OR is there any better way to achieve this. My DAL is generated from LLBLGen Pro (ORM) but you are open to suggest me a solution. Thanks. Edit: I am using Telerik controls so I can get all data in DataTable like DataTable dtProducts = this.radGridView1.DataSource as DataTable;

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  • Advice on displaying and allowing editing of data using ASP.NET MVC?

    - by Remnant
    I am embarking upon my first ASP.NET MVC project and I would like to get some input on possible ways to display database data and general best practice. In short, the body of my webpage will show data from my database in a table like format, with each table row showing similar data. For example: Name Age Position Date Joined Jon Smith 23 Striker 18th Mar 2005 John Doe 38 Defender 3rd Jan 1988 In terms of functionality, primarily I’d like to give the user the ability to edit the data and, after the edit, commit the edit to the database and refresh the view.The reason I want to refresh the view is because the data is date ordered and I will need to re-sort if the user edits a date field. My main question is what architecture / tools would be best suited to this fulfil my requirements at a high level? From the research I have done so far my initial conclusions were: ADO.NET for data retrieval. This is something I have used before and feel comfortable with. I like the look of LINQ to SQL but don’t want to make the learning curve any steeper for my first outing into MVC land just yet. Partial Views to create a template and then iterate through a datatable that I have pulled back from my database model. jQuery to allow the user to edit data in the table, error check edited data entries etc. Also, my intial view was that caching the data would not be a key requirement here. The only field a user will be able to update is the field and, if they do, I will need to commit that data to the database immediately and then refresh the view (as the data is date sorted). Any thoughts on this? Alternatively, I have seen some jQuery plug-ins that emulate a datagrid and provide associated functionality. My first thoughts are that I do not need all the functionality that comes with these plug-ins (e.g. zebra striping, ability to sort by column using sort glyph in column headers etc .) and I don’t really see any benefit to this over and above the solution I have outlined above. Again, is there reason to reconsider this view? Finally, when a user edits a date , I will need to refresh the view. In order to do this I had been reading about Html.RenderAction and this seemed like it may be a better option than using Partial Views as I can incorporate application logic into the action method. Am I right to consider Html.RenderAction or have I misunderstood its usage? Hope this post is clear and not too long. I did consider separate posts for each topic (e.g. Partial View vs. Html.RenderAction, when to use jQury datagrid plug-in) but it feels like these issues are so intertwined that they need to be dealt with in contect of each other. Thanks

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  • Graph colouring algorithm: typical scheduling problem

    - by newba
    Hi, I'm training code problems like UvA and I have this one in which I have to, given a set of n exams and k students enrolled in the exams, find whether it is possible to schedule all exams in two time slots. Input Several test cases. Each one starts with a line containing 1 < n < 200 of different examinations to be scheduled. The 2nd line has the number of cases k in which there exist at least 1 student enrolled in 2 examinations. Then, k lines will follow, each containing 2 numbers that specify the pair of examinations for each case above. (An input with n = 0 will means end of the input and is not to be processed). Output: You have to decide whether the examination plan is possible or not for 2 time slots. Example: Input: 3 3 0 1 1 2 2 0 9 8 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 Ouput: NOT POSSIBLE. POSSIBLE. I think the general approach is graph colouring, but I'm really a newb and I may confess that I had some trouble understanding the problem. Anyway, I'm trying to do it and then submit it. Could someone please help me doing some code for this problem? I will have to handle and understand this algo now in order to use it later, over and over. I prefer C or C++, but if you want, Java is fine to me ;) Thanks in advance

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  • Tool for documentation of the fields of a database ?

    - by Jerome WAGNER
    Hello, I need to add documentation to all fields of 2 databases (1 postgresql & 1 sql server), around 100 tables each. What tool would be convenient to do that (reverse the schema + add documentation manually on all fields) ? My favors would go to an open source tool with a graphical & xml output. Thanks for your help Jerome WAGNER

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  • How to add an "Export to ebook" feature to a site?

    - by systempuntoout
    How could i add to a blog or site in general a feature that let users export the content to epub format or some other open ebook formats? It's not a feature that i normally see on most of the site i browse every day (some has export to pdf that is not great as ebook format), do you think it is feasible? I own an ebook reader and reading saved html to pdf pages is not so good. I'm searching for a general solution here so i have not specified any specific technology; if you have some sites that offer this feature i would like to try them. thanks

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  • Delphi, how to make independent windows

    - by Roy M Klever
    I have an application that uses tabs like the Chrome browser. Now I want to be able to open more forms and not be limited to only one form. These forms should act the same but if I close main form all forms are closed. How can I make all forms be equal, so no matter which form I close it only closes that form and not exit application before all forms are closed? Any ideas? Kind Regards Roy M Klever

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  • Object database for website

    - by Damian
    I was planning to use db4o for a website. It's a microblog site with small posts and comments developed in java. The thing is I contacted db4o support asking if db4o would be suitable for a website, and they answered me that only for websites with low concurrency. That means with few requests? So, now I think db4o will not be a good choice. Do you know if there is any object database for java suitable for a website?

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  • 7 Card Poker Hand Evaluator

    - by Peter
    Hey, Does anyone know a fast algorithm for evaluating 7 card poker hands? Something which is more efficient than simply brute-force checking a every 21 5-card combination of hands from a set of 7. Cheers, Pete

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  • How should I provide access to this custom DAL?

    - by Casey
    I'm writing a custom DAL (VB.NET) for an ordering system project. I'd like to explain how it is coded now, and receive some alternate ideas to make coding against the DAL easier/more readable. The DAL is part of an n-tier (not n-layer) application, where each tier is in it's own assembly/DLL. The DAL consists of several classes that have specific behavior. For instance, there is an Order class that is responsible for retrieving and saving orders. Most of the classes have only two methods, a "Get" and a "Save," with multiple overloads for each. These classes are marked as Friend and are only visible to the DAL (which is in it's own assembly). In most cases, the DAL returns what I will call a "Data Object." This object is a class that contains only data and validation, and is located in a common assembly that both the BLL and DAL can read. To provide public access to the DAL, I currently have a static (module) class that has many shared members. A simplified version looks something like this: Public Class DAL Private Sub New End Sub Public Shared Function GetOrder(OrderID as String) as OrderData Dim OrderGetter as New OrderClass Return OrderGetter.GetOrder(OrderID) End Function End Class Friend Class OrderClass Friend Function GetOrder(OrderID as string) as OrderData End Function End Class The BLL would call for an order like this: DAL.GetOrder("123456") As you can imagine, this gets cumbersome very quickly. I'm mainly interested in structuring access to the DAL so that Intellisense is very intuitive. As it stands now, there are too many methods/functions in the DAL class with similar names. One idea I had is to break down the DAL into nested classes: Public Class DAL Private Sub New End Sub Public Class Orders Private Sub New End Sub Public Shared Function Get(OrderID as string) as OrderData End Function End Class End Class So the BLL would call like this: DAL.Orders.Get("12345") This cleans it up a bit, but it leaves a lot of classes that only have references to other classes, which I don't like for some reason. Without resorting to passing DB specific instructions (like where clauses) from BLL to DAL, what is the best or most common practice for providing a single point of access for the DAL?

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  • Are web-safe colors still relevant?

    - by Gavin Miller
    Since the vast majority of monitors are 16-bit color or more, including mobile devices, does it make sense to even consider web-safe colors when choosing color schemes? Or is it something that ought to be relegated to history as a piece of trivia? For those of you that don't know what web-safe colors are: Another set of 216 color values is commonly considered to be the "web-safe" color palette, developed at a time when many computer displays were only capable of displaying 256 colors. A set of colors was needed that could be shown without dithering on 256-color displays; the number 216 was chosen partly because computer operating systems customarily reserved sixteen to twenty colors for their own use; it was also selected because it allows exactly six shades each of red, green, and blue (6 × 6 × 6 = 216). The list of colors is often presented as if it has special properties that render them immune to dithering. In fact, on 256-color displays applications can set a palette of any selection of colors that they choose, dithering the rest. These colors were chosen specifically because they matched the palettes selected by the then leading browser applications. [Wikipedia]

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