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How to generate many random various numbers?

By , 9 Sep 2011
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public IEnumerable<int> GenerateRandomSequence(int min, int max)
    var rnd = new Random();
    return Enumerable.Range( min, max-min ).OrderBy( n => rnd.Next() );

You'll need a reference to System.Core to use this, and a version of .NET that supports LINQ.

If you're using .NET 4, you can use multiple cores to parallelize it, just add ".AsParallel()" to the end of the Range function:

return Enumerable.Range( min, max-min ).AsParallel().OrderBy( n => rnd.Next() );

NOTE: AsParallel() is not a good way to accomplish this, as the Random class is not thread safe. For a parallel and thread safe solution, see the article mentioned in the comments below (Thanks to Richard Deeming for pointing this out! Smile | :) )


To use:

foreach(var number in GenerateRandomSequence(10,500))
   // Do something with number

The above code generates a non-repeating random sequence of numbers between 10 and 500.


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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Comments and Discussions

GeneralRe: After running tests, I have to conclude that Richard is corr... Pinmembermyker9-Sep-11 12:25 
GeneralRe: Never mind. I must have written that comment before drinking... PinmemberHenry.Ayoola5-Sep-11 4:03 
GeneralReason for my vote of 5 Creative.. PinmemberPravin Patil, Mumbai13-Sep-11 0:29 
GeneralThe Random class is not thread-safe, so adding ".AsParallel(... PinmemberRichard Deeming9-Sep-11 8:41 
GeneralRe: Good catch, Richard! That's really good to know. I'm remov... Pinmembermyker9-Sep-11 11:40 
GeneralRe: Richard... after further investigation, the AsParallel() is ... Pinmembermyker9-Sep-11 11:51 
GeneralHowever, it doesn't give a uniform distribution. PinmemberHenry.Ayoola2-Sep-11 4:31 
GeneralRe: I'm not sure I understand your comment. Can you explain fur... Pinmembermyker2-Sep-11 5:12 
GeneralReason for my vote of 5 Nice approach using LINQ PinmemberShahin Khorshidnia1-Sep-11 14:32 
GeneralRe: Thank you! Glad to be of some help. Pinmembermyker1-Sep-11 17:30 

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