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  • Possible applications of algorithm devised for differentiating between structured vs random text

    - by rooznom
    I have written a program that can rapidly (within 5 sec on a 2GB RAM desktop, 2.33 Ghz CPU) differentiate between structured text (e.g english text) and random alphanumeric strings. It can also provide a probability score for the prediction. Are there any practical applications/uses of such a program. Note that the program is based on entropy models and does not have any dictionary comparisons in its workflow. Thanks in advance for your responses

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  • Random Vector within a cone

    - by Paul
    I'm looking to create a random vector within a cone given the radius (base). It feels like I've been traversing through many pages on the internet and still I'm no further forward to getting an answer. I was thinking I could get a point within the base of the cone and have it point towards the apex (then just use the inverse of that for my animation) but this seems like an incredibly long winded approach.

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  • How to pick random (small) data samples using Map/Reduce?

    - by Andrei Savu
    I want to write a map/reduce job to select a number of random samples from a large dataset based on a row level condition. I want to minimize the number of intermediate keys. Pseudocode: for each row if row matches condition put the row.id in the bucket if the bucket is not already large enough Have you done something like this? Is there any well known algorithm? A sample containing sequential rows is also good enough. Thanks.

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  • How does this C# asp.net random password code work?

    - by quakkels
    Hello all, I'm new to .NET and C# and I'm trying to figure out how this code works: public static string CreateRandomPassword(int PasswordLength) { String _allowedChars = "abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNOPQRSTUVWXYZ23456789"; Byte[] randomBytes = new Byte[PasswordLength]; RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider(); rng.GetBytes(randomBytes); char[] chars = new char[PasswordLength]; int allowedCharCount = _allowedChars.Length; for(int i = 0;i<PasswordLength;i++) { /// /// I don't understand how this line works: /// chars[i] = _allowedChars[(int)randomBytes[i] % allowedCharCount]; } return new string(chars); } I think I've got a pretty good handle on most of this. I haven't been able to understand the following line: chars[i] = _allowedChars[(int)randomBytes[i] % allowedCharCount]; I understand that the code generates random binary numbers and uses those random numbers in the for loop to select a character from the _allowedChars string. What I don't get is why this code uses the modulous operator (%) to get the _allowedChars index value. Thanks for any help

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  • How to generate a good random seed to pass to srand()?

    - by zr
    Hi, I am writing a C++ program which needs to create a temporary file for its internal usage. I would like to allow concurrent executions of the program by running multiple proccesses, so the temporary file name needs to be randomized, that way each spawned process will generate a unique temporary file name for its own use. I am using rand() to generate random characters for part of the file name, so i need to initialize the random number generator's seed using srand(). What options are there for passing a good argument to srand() such that two processes will not be initialized with the same seed value? My code needs to work both on Windows and pn Linux TIA.

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  • Oracle aggregate function to return a random value for a group?

    - by tpdi
    The standard SQL aggregate function max() will return the highest value in a group; min() will return the lowest. Is there an aggregate function in Oracle to return a random value from a group? Or some technique to achieve this? E.g., given the table foo: group_id value 1 1 1 5 1 9 2 2 2 4 2 8 The SQL query select group_id, max(value), min(value), some_aggregate_random_func(value) from foo group by group_id; might produce: group_id max(value), min(value), some_aggregate_random_func(value) 1 9 1 1 2 8 2 4 with, obviously, the last column being any random value in that group.

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  • What's the best way to return a random line in a text file using C?

    - by jeremy Ruten
    What's the best way to return a random line in a text file using C? It has to use the standard I/O library (<stdio.h>) because it's for Nintendo DS homebrew. Clarifications: Using a header in the file to store the number of lines won't work for what I want to do. I want it to be as random as possible (the best being if each line has an equal probability of being chosen as every other line.) The file will never change while the program is being run. (It's the DS, so no multi-tasking.)

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  • How hard is it to create a not-so-random number generator?

    - by Duracell
    Backstory: So I was driving to band practice this evening. My car has a USB port where you can plug in a USB stick with MP3 files on it and the stereo will play them. I have about 100 MP3s on my stick so I pushed the 'Random' button. So from here to band practice, it played: Track 22 Track 45 Track 4 Track 11 Track 87 Track 66 Track 98 Then on the way home, it played Track 16 Track 27 Track 33 And then I stopped at the petrol station. I filled up, got back in the car and the stereo fired up again. It played Track 22 Track 45 Track 4 Track 11 Track 87 I thought, WTF? What's with this 'random' generator? What are they using as a seed, if not time? Is a car stereo so memory-tight that it can't even use the C stdlib? Does anyone know how this kind of thing happens?

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  • How to make a random number generator in matlab that is based on percentages?

    - by Ben Fossen
    I am currently using the built in random number generator. for example nAsp = randi([512, 768],[1,1]); 512 is the lower bound and 768 is the upper bound, the random number generator chooses a number from between these two values. What I want is to have two ranges for nAsp but I want one of them to get called 25% of the time and the other 75% of the time. Then gets plugged into he equation. Does anyone have any ideas how to do this or if there is a built in function in matlab already? for example nAsp = randi([512, 768],[1,1]); gets called 25% of the time nAsp = randi([690, 720],[1,1]); gets called 75% of the time

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  • Random select is not always returning a single row.

    - by Lieven
    The intention of following (simplified) code fragment is to return one random row. Unfortunatly, when we run this fragment in the query analyzer, it returns between zero and three results. As our input table consists of exactly 5 rows with unique ID's and as we perform a select on this table where ID equals a random number, we are stumped that there would ever be more than one row returned. Note: among other things, we already tried casting the checksum result to an integer with no avail. DECLARE @Table TABLE ( ID INTEGER IDENTITY (1, 1) , FK1 INTEGER ) INSERT INTO @Table SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 SELECT * FROM @Table WHERE ID = ABS(CHECKSUM(NEWID())) % 5 + 1

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  • How to generate random strings that match a given regexp?

    - by Pies
    Duplicate: Random string that matches a regexp No, it isn't. I'm looking for an easy and universal method, one that I could actually implement. That's far more difficult than randomly generating passwords. I want to create an application that takes a regular expression, and shows 10 randomly generated strings that match that expression. It's supposed to help people better understand their regexps, and to decide i.e. if they're secure enough for validation purposes. Does anyone know of an easy way to do that? One obvious solution would be to write (or steal) a regexp parser, but that seems really over my head. I repeat, I'm looking for an easy and universal way to do that. Edit: Brute force approach is out of the question. Assuming the random strings would just be [a-z0-9]{10} and 1 million iterations per second, it would take 65 years to iterate trough the space of all 10-char strings.

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  • Learning HTML5 - Sample Sites

    - by Albers
    Part of the challenge with HTML5 is understanding the range of different technologies and finding good samples. The following are some of the sites I have found most useful. IE TestDrive http://ie.microsoft.com/testdrive/ A good set of demos using touch, appcache, IndexDB, etc. Some of these only work with IE10. Be sure to click the "More Demos" link at the bottom for a longer list of Demos in a nicely organized list form. Chrome Experiments http://www.chromeexperiments.com/ Chrome browser-oriented sumbitted sites with a heavy emphasis on display technologies (WebGL & Canvas) Adobe Expressive Web http://beta.theexpressiveweb.com/ Adobe provides a dozen HTML5 & CSS3 samples. I seem to end up playing the "Breakout" style Canvas demo every time I visit the site. Mozilla Demo Studio https://developer.mozilla.org/en-US/demos/tag/tech:html5/ About 100 varied HTML5-related submitted web sites. If you click the "Browse By Technology" button there are other samples for File API, IndexedDB, etc. Introducing HTML5 samples http://html5demos.com/ Specific Tech examples related to the "Introducing HTML5" book by Bruce Lawson & Remy Sharp HTML5 Gallery http://html5gallery.com/ HTML5 Gallery focuses on "real" sites - sites that were not specifically intended to showcase a particular HTML5 feature. The actual use of HTML5 tech can vary from link to link, but it is useful to see real-world uses. FaceBook Developers HTML5 Showcase http://developers.facebook.com/html5/showcase/ A good list of high profile HTML5 applications, games and demos (including the Financial Times, GMail, Kindle web reader, and Pirates Love Daisies). HTML5 Studio http://studio.html5rocks.com/ Another Google site - currently 14 samples of concepts like slideshows, Geolocation, and WebGL using HTML5.

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  • I need a step-by-step Sample Programming Tutorial (book or website)

    - by Albert Y.
    Can anyone recommend a step-by-step programming tutorial (either book or website) where they walk you through designing a complex program and explain what they are coding & why? Language doesn't matter, but preferably something like Java, Python, C++, or C and not web based. I am a new programmer and I am looking for good examples that will teach me how to program something more complex than simple programs given in programming textbooks.

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  • SQL SERVER Simple Installation of Master Data Services (MDS) and Sample Packages Very Easy

    I twitted recently about: ‘Installing #sql Server 2008 R2 – Master Data Services. Painless.‘ After doing so, I got quite a few emails from other users as to why I thought it was painless. The reason was very simple- I was able to install it rather quickly on my laptop without any issues. There were [...]...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • State Design Pattern .NET Code Sample

    using System;using System.Collections.Generic;using System.Linq;using System.Text;class Program{ static void Main(string[] args) { Person p1 = new Person("P1"); Person p2 = new Person("P2"); p1.EatFood(); p2.EatFood(); p1.Vomit(); p2.Vomit(); }}interface StomachState{ void Eat(Person p); void Vomit(Person p);}class StomachFull : StomachState{ public void Eat(Person p) { Console.WriteLine("Can't eat more."); } public void Vomit(Person p) { Console.WriteLine("I've just Vomited."); p.StomachState = new StomachEmpty(); }}class StomachEmpty : StomachState{ public void Eat(Person p) { Console.WriteLine("I've just had food."); p.StomachState = new StomachFull(); } public void Vomit(Person p) { Console.WriteLine("Nothing to Vomit."); }}class Person{ private StomachState stomachState; private String personName; public Person(String personName) { this.personName = personName; StomachState = new StomachEmpty(); } public StomachState StomachState { get { return stomachState; } set { stomachState = value; Console.WriteLine(personName + " Stomach State Changed to " + StomachState.GetType().Name); Console.WriteLine("***********************************************\n"); } } public Person(StomachState StomachState) { this.StomachState = StomachState; } public void EatFood() { StomachState.Eat(this); } public void Vomit() { StomachState.Vomit(this); }} span.fullpost {display:none;}

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  • Xna GS 4 Animation Sample bone transforms not copying correctly

    - by annonymously
    I have a person model that is animated and a suitcase model that is not. The person can pick up the suitcase and it should move to the location of the hand bone of the person model. Unfortunately the suitcase doesn't follow the animation correctly. it moves with the hand's animation but its position is under the ground and way too far to the right. I haven't scaled any of the models myself. Thank you. The source code (forgive the rough prototype code): Matrix[] tran = new Matrix[man.model.Bones.Count];// The absolute transforms from the animation player man.model.CopyAbsoluteBoneTransformsTo(tran); Vector3 suitcasePos, suitcaseScale, tempSuitcasePos = new Vector3();// Place holders for the Matrix Decompose Quaternion suitcaseRot = new Quaternion(); // The transformation of the right hand bone is decomposed tran[man.model.Bones["HPF_RightHand"].Index].Decompose(out suitcaseScale, out suitcaseRot, out tempSuitcasePos); suitcasePos = new Vector3(); suitcasePos.X = tempSuitcasePos.Z;// The axes are inverted for some reason suitcasePos.Y = -tempSuitcasePos.Y; suitcasePos.Z = -tempSuitcasePos.X; suitcase.Position = man.Position + suitcasePos;// The actual Suitcase properties suitcase.Rotation = man.Rotation + new Vector3(suitcaseRot.X, suitcaseRot.Y, suitcaseRot.Z); I am also copying the bone transforms from the animation player in the Person class like so: // The transformations from the AnimationPlayer Matrix[] skinTrans = new Matrix[model.Bones.Count]; skinTrans = player.GetBoneTransforms(); // copy each transformation to its corresponding bone for (int i = 0; i < skinTrans.Length; i++) { model.Bones[i].Transform = skinTrans[i]; }

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  • SQL Server DMVs in Action - Sample Chapter

    Read the first chapter of this new book on DMVs. Free trial of SQL Backup™“SQL Backup was able to cut down my backup time significantly AND achieved a 90% compression at the same time!” Joe Cheng. Download a free trial now.

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  • A sample Memento pattern: Is it correct?

    - by TheSilverBullet
    Following this query on memento pattern, I have tried to put my understanding to test. Memento pattern stands for three things: Saving state of the "memento" object for its successful retrieval Saving carefully each valid "state" of the memento Encapsulating the saved states from the change inducer so that each state remains unaltered Have I achieved these three with my design? Problem This is a zero player game where the program is initialized with a particular set up of chess pawns - the knight and queen. Then program then needs to keep adding set of pawns or knights and queens so that each pawn is "safe" for the next one move of every other pawn. The condition is that either both pawns should be placed, or none of them should be placed. The chessboard with the most number of non conflicting knights and queens should be returned. Implementation I have 4 classes for this: protected ChessBoard (the Memento) private int [][] ChessBoard; public void ChessBoard(); protected void SetChessBoard(); protected void GetChessBoard(int); public Pawn This is not related to memento. It holds info about the pawns public enum PawnType: int { Empty = 0, Queen = 1, Knight = 2, } //This returns a value that shown if the pawn can be placed safely public bool IsSafeToAddPawn(PawnType); public CareTaker This corresponds to caretaker of memento This is a double dimentional integer array that keeps a track of all states. The reason for having 2D array is to keep track of how many states are stored and which state is currently active. An example: 0 -2 1 -1 2 0 - This is current state. With second index 0/ 3 1 - This state has been saved, but has been undone private int [][]State; private ChessBoard [] MChessBoard; //This gets the chessboard at the position requested and assigns it to originator public ChessBoard GetChessBoard(int); //This overwrites the chessboard at given position public void SetChessBoard(ChessBoard, int); private int [][]State; public PlayGame (This is the originator) private bool status; private ChessBoard oChessBoard; //This sets the state of chessboard at position specified public SetChessBoard(ChessBoard, int); //This gets the state of chessboard at position specified public ChessBoard GetChessBoard(int); //This function tries to place both the pawns and returns the status of this attempt public bool PlacePawns(Pawn);

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  • SQL Profiler Through StreamInsight Sample Solution

    In this postI show how you can use StreamInsight to take events coming from SQL Server Profiler in real-time and do some analytics whilst the data is in flight.  Here is the solution for that post.  The download contains Project that reads events from a previously recorded trace file Project that starts a trace and captures events in real-time from a custom trace definition file (Included) It is a very simple solution and could be extended.  Whilst this example traces against SQL Server it would be trivial to change this so it profiles events in Analysis Services.       Enjoy.

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