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  • Algorithm for generating an array of non-equal costs for a transport problem optimization

    - by Carlos
    I have an optimizer that solves a transportation problem, using a cost matrix of all the possible paths. The optimiser works fine, but if two of the costs are equal, the solution contains one more path that the minimum number of paths. (Think of it as load balancing routers; if two routes are same cost, you'll use them both.) I would like the minimum number of routes, and to do that I need a cost matrix that doesn't have two costs that are equal within a certain tolerance. At the moment, I'm passing the cost matrix through a baking function which tests every entry for equality to each of the other entries, and moves it a fixed percentage if it matches. However, this approach seems to require N^2 comparisons, and if the starting values are all the same, the last cost will be r^N bigger. (r is the arbitrary fixed percentage). Also there is the problem that by multiplying by the percentage, you end up on top of another value. So the problem seems to have an element of recursion, or at least repeated checking, which bloats the code. The current implementation is basically not very good (I won't paste my GOTO-using code here for you all to mock), and I'd like to improve it. Is there a name for what I'm after, and is there a standard implementation? Example: {1,1,2,3,4,5} (tol = 0.05) becomes {1,1.05,2,3,4,5}

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  • how to store passwords in database?

    - by rgksugan
    I use jsp and servlets in my web application. i need to store passwords in the database. I found that hashing will be the best way to do that. I used this code to do it. java.security.MessageDigest d = null; d = java.security.MessageDigest.getInstance("SHA-1"); d.reset(); d.update(pass.getBytes("UTF-8")); byte b[] = d.digest(); String tmp = (new BASE64Encoder()).encode(b); When i tried to print the value of tmp, i get some other value.i guess its the hash value of the password. But when i persist this data to the database the original password gets saved there other than the value in tmp.. What is the problem???

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  • Design Solution For Storing-Fetching Images

    - by Chaitanya
    This is a design doubt am facing, I have a collection of 1500 images which are to be displayed on an asp.net page, the images to be displayed differ from one page to another, the count of these images will increase in the time to come, a.) is it a good idea to have the images on the database, but the round trip time to fetch the images from the database might be high. b.) is it good to have all the images on a directory, and have a virtual file system over it, and the application will access the images from the directory Do we have in particular any design strategy in a traditional database for fetching images with the least round trip time, does any solution other than usage of a traditional database exists? ps: I use SQL Server to store these images.

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  • Modifying a MySQL database on a Ruby on Rails install

    - by James W
    Hello, sorry if this questions is overly basic or has been asked before but I simply cannot figure it out. On my Ruby on Rails site, I have a controller that accesses the fields of a table in my database and displays their "Name" field as a drop-down menu in one of my views. My problem is I need to change the options of that dropdown menu so I need a way to get into the MySQL database and change the values of those fields. Anyone know of a way to do this? It would be much appreciated. Thank you.

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  • Regex: match a non nested code block

    - by Sylvanas Garde
    I am currently writing a small texteditor. With this texteditor users are able to create small scripts for a very simple scripting engine. For a better overview I want to highlight codeblocks with the same command like GoTo(x,y) or Draw(x,y). To achieve this I want to use Regular Expresions (I am already using it to highlight other things like variables) Here is my Expression (I know it's very ugly): /(?<!GoTo|Draw|Example)(^(?:GoTo|Draw|Example)\(.+\)*?$)+(?!GoTo|Draw|Example)/gm It matches the following: lala GoTo(5656) -> MATCH 1 sdsd GoTo(sdsd) --comment -> MATCH 2 GoTo(23329); -> MATCH 3 Test() GoTo(12) -> MATCH 4 LALA Draw(23) -> MATCH 5 Draw(24) -> MATCH 6 Draw(25) -> MATCH 7 But what I want to achieve is, that the complete "blocks" of the same command are matched. In this case Match 2 & 4 and Match 5 & 6 & 7 should be one match. Tested with http://regex101.com/, the programming lanuage is vb.net. Any advise would be very useful, Thanks in advance!

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  • populate object graph from database

    - by Rama
    Hi, I would like to know the best way to populate an object that has a collection of child objects and each child object may inturn have a collection of objects, from database without making multiple calls to the database to get child objects for each object. basically in hierarchical format something like for example a customer has orders and each order has order items. is it best to retrieve the data in xml format (SQL server 2005), or retrieve a dataset by joining the related tables together and then map that the data to the object? thanks in advance for your help.

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  • What is an efficient way to find a non-colliding rectangle nearest to a location

    - by hyn
    For a 2D game I am working on, I am using y axis sorting in a simple rectangle-based collision detection. This is working fine, and now I want to find the nearest empty rectangle at a given location with a given size, efficiently. How can I do this? Is there an algorithm? I could think of a simple brute force grid test (with each grid the size of the empty space we're looking for) but obviously this is slow and not even a complete test.

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  • Determining which database instance makes biggest IO

    - by user2008937
    Assuming that I have a dedicated server on which I am running multiple instances of mysql and postresql servers. How without iotop determine which instance in particular time (proc/pid/io shows data collected in some peroid of time) makes the biggest IO (so it increases IOWAIT)? When lots of ppl do something on DB then I clearly see which instance is making the load because of high cpu usage, but I had a situation when the cpu usage was just normal, but very high iowait made a huge load on server and i had problem finding process that was making some outstanding IO

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  • Storing And Using Microsoft User Account Credentials in SQL Server 2008 database

    - by user337501
    I'm not exactly positive how to word this for the sake of the title so please forgive me. Also I can't seem to figure out how to even google this question, so I'm hoping that I can get a lead in the right direction. Part of my software(VB.NET App) requires the ability to access/read/write a shared network folder. I have an option for the user to specify any credentials that might be needed to access said folder. I want to store these credentials given in the SQL Server database as part of the config (I have a table which contains configuration). My concern is that the password for the user account will be unencrpyted. Yet, if I encrypt the password the VB.NET App And/Or database will be unable to use the credentials for file i/o operations unless the Password is unencrypted before use. I'm fishing for suggestions on how to better handle this situation.

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  • Finding a list of indices from master array using secondary array with non-unique entries

    - by fideli
    I have a master array of length n of id numbers that apply to other analogous arrays with corresponding data for elements in my simulation that belong to those id numbers (e.g. data[id]). Were I to generate a list of id numbers of length m separately and need the information in the data array for those ids, what is the best method of getting a list of indices idx of the original array of ids in order to extract data[idx]? That is, given: a=numpy.array([1,3,4,5,6]) # master array b=numpy.array([3,4,3,6,4,1,5]) # secondary array I would like to generate idx=numpy.array([1,2,1,4,2,0,3]) The array a is typically in sequential order but it's not a requirement. Also, array b will most definitely have repeats and will not be in any order. My current method of doing this is: idx=numpy.array([numpy.where(a==bi)[0][0] for bi in b]) I timed it using the following test: a=(numpy.random.uniform(100,size=100)).astype('int') b=numpy.repeat(a,100) timeit method1(a,b) 10 loops, best of 3: 53.1 ms per loop Is there a better way of doing this?

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  • Visual Studio: Debuggin non localhost domain, locally

    - by Skawful
    I have an entry in my hosts file that points somesite.com to 127.0.0.1 (localhost) so that I can test certain aspects of my web app (i goto http://somesite.com in a browser to test). Can someone suggest a way to debug a setup like this (in visual studio) that does not include using http://localhost? I understand that this can most likely be done using remote debugger, if that is the best way can someone explain how thats setup (or a link to a good article).

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  • How to manually verify a user against the asp.net memberhip database

    - by Ekk
    I would like to know how I can verify a user's credential against an existing asp.net membership database. The short story is that we want provide single sign on access. So what I've done is to connect directly to the membership database and tried to run a sql query against the aspnet_Membership table: private bool CanLogin(string userName, string password) { // Check DB to see if the credential is correct try { string passwordHash = FormsAuthentication.HashPasswordForStoringInConfigFile(password, "SHA1"); string sql = string.Format("select 1 from aspnet_Users a inner join aspnet_Membership b on a.UserId = b.UserId and a.applicationid = b.applicationid where a.username = '{0}' and b.password='{1}'", userName.ToLowerInvariant(), passwordHash); using (SqlConnection sqlConn = new SqlConnection(ConfigurationManager.ConnectionStrings["LocalSqlServer"].ConnectionString)) using (SqlCommand sqlCmd = new SqlCommand(sql, sqlConn)) { sqlConn.Open(); int count = sqlCmd.ExecuteNonQuery(); sqlConn.Close(); return count == 1; } } catch (Exception ex) { return false; } } The problem is the password value, does anyone know how the password it is hashed?

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  • non-cached RSLs in Flex?

    - by SteMa
    I have a project that is for several customers, the only difference is in the DB, everything else looks the same, except for the main page's text. That is loaded from an external swf file. I created a library, compiled it as an swc, imported it and using it as an RSL. The problem is that if once I've opened the page, and afterwards update the rsl (because changes in the text are needed), than it's already cached by the browser (not the flashplayer's cache but we shouldn't discuss this please!) and the updated swf won't be loaded. If I use it as an external, the page won't even start up (the browser says it's loaded, but it's blank, not even the loading progess bar of flex appear) <local:MainPage includeIn="default" currentState="{MainPageState}" id="Page" width="100%" height="100%" /> this is the code on the main page, if I comment this out, than the whole thing loads, even with the use of the "external" link-type. If it helps, in the design view, I see the component, but I get a warning for the library: Design mode could not load MainPage.swc. It may be incompatible with this SDK, or invalid. (DesignAssetLoader.CompleteTimeout)

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  • Storing images in a Microsoft SQL Server 2005 database

    - by Rekreativc
    Hello! I have a question about storing an image in a database. I know this topic has been discussed before, however I feel that in my case this is actually a good idea - the images will be small (none should be as large as 1MB) and there shouldn't be too many. I like the idea of not worrying about IO permissions etc. Anyway I have a problem when storing the image (byte[]) to the database type image. Here is my code: OleDbCommand comm = new OleDbCommand(strSql, Program.GetConnection()); comm.Parameters.Add("?", SqlDbType.Image).Value = bytearr; comm.ExecuteNonQuery(); Everything compiles fine, however when I run it, the code only saves the value 63 (0x3F) into the field - no matter which image I am trying to save. What could be the problem? Thank you for your help.

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  • "Did you mean" feature on a dictionary database

    - by Hazar
    I have a ~300.000 row table; which includes technical terms; queried using PHP and MySQL + FULLTEXT indexes. But when I searching a wrong typed term; for example "hyperpext"; naturally giving no results. I need to "compansate" little writing errors and getting nearest record from database. How I can accomplish such feaure? I know (actually, learned today) about Levenshtein distance, Soundex and Metaphone algorithms but currently not having a solid idea to implement this to querying against database. Best regards. (Sorry about my poor English, I'm trying to do my best)

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  • Best idea dataserver serving small pictures 40 ko

    - by Nicolas Manzini
    I'm designing the server structure for my application in case things go well. I have one server DB connected to multiple server who process connections. All those with lots of RAM and fast processors. (still looking for a way to use the multithread because now it's dumb apache php... so loooots of ram needed). Upon an answer from those servers, the client can then connect to another server to retrieve pictures using the address he previously got from the db. Is it a good idea to have one database server with let's say nginx and ssd disk having to send all pictures to everybody? or should I have multiple server accessing to a shared ssd disk drive or multiple disk updating each other? Also should I put a lot of RAM on the database server? because probably there wont be a picture more popular than another.

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  • xstream handles non-english character

    - by Yan Cheng CHEOK
    I have the following code : /* * To change this template, choose Tools | Templates * and open the template in the editor. */ package helloworld; import com.thoughtworks.xstream.XStream; import java.io.File; import java.io.FileOutputStream; import java.io.InputStream; import java.io.OutputStream; import javax.swing.JOptionPane; /** * * @author yccheok */ public class Test { @SuppressWarnings("unchecked") public static <A> A fromXML(Class c, File file) { XStream xStream = new XStream(); InputStream inputStream = null; try { inputStream = new java.io.FileInputStream(file); Object object = xStream.fromXML(inputStream); if (c.isInstance(object)) { return (A)object; } } catch (Exception exp) { exp.printStackTrace(); } finally { if (inputStream != null) { try { inputStream.close(); inputStream = null; } catch (java.io.IOException exp) { exp.printStackTrace(); return null; } } } return null; } @SuppressWarnings("unchecked") public static <A> A fromXML(Class c, String filePath) { return (A)fromXML(c, new File(filePath)); } public static boolean toXML(Object object, File file) { XStream xStream = new XStream(); OutputStream outputStream = null; try { outputStream = new FileOutputStream(file); xStream.toXML(object, outputStream); } catch (Exception exp) { exp.printStackTrace(); return false; } finally { if (outputStream != null) { try { outputStream.close(); outputStream = null; } catch (java.io.IOException exp) { exp.printStackTrace(); return false; } } } return true; } public static boolean toXML(Object object, String filePath) { return toXML(object, new File(filePath)); } public static void main(String args[]) { String s = "\u6210\u4EA4\u91CF"; // print ??? System.out.println(s); // fine! show ??? JOptionPane.showMessageDialog(null, s); toXML(s, "C:\\A.XML"); String o = fromXML(String.class, "C:\\A.XML"); // show ??? JOptionPane.showMessageDialog(null, o); } } I run the following code through command prompt in Windows Vista. 1) May I know why System.out.println unable to print out Chinese Character in console? 2) I open up the xstream file. The saved value is <string>???</string> How can I make xstream save Chinese Character correctly? Thanks.

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  • Using SQL Server profiler from 2008 against R2 database

    - by Chris Lively
    On my dev machine I have the management studio tools installed from SQL Server 2008. However, one of the sql server boxes I need to profile against is running R2. Because of this, when I start the profiler and connect to that server all of the templates are gone. If I go to Edit the templates, the R2 server type isn't available as an option. Do I have to upgrade my local toolset to R2 or is there some other way around this? Note, that if I create a template and save it the next time I connect to the server that saved template isn't available.

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  • Is there are standard way to store a database schema outside a python app

    - by acrosman
    I am working on a small database application in Python (currently targeting 2.5 and 2.6) using sqlite3. It would be helpful to be able to provide a series of functions that could setup the database and validate that it matches the current schema. Before I reinvent the wheel, I thought I'd look around for libraries that would provide something similar. I'd love to have something akin to RoR's migrations. xml2ddl doesn't appear to be meant as a library (although it could be used that way), and more importantly doesn't support sqlite3. I'm also worried about the need to move to Python 3 one day given the lack of recent attention to xml2ddl. Are there other tools around that people are using to handle this?

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