more than 1 sequence of random numbers c#, linq

i was using this code to generate a random sequence of numbers:

va开发者_如何学Cr sequence = Enumerable.Range(0, 9).OrderBy(n => n * n * (new Random()).Next());

everything was ok till i need more than one sequence, in this code i call the routine 10 times, and the results are my problem, all the sequence are equal.

        int i = 0;
        while (i<10)
        {
            Console.Write("{0}:",i);
            var sequence = Enumerable.Range(0, 9).OrderBy(n => n * n * (new Random()).Next());
            sequence.ToList().ForEach(x=> Console.Write(x));
            i++;
            Console.WriteLine();
        }

Can someone give me a hint of how actually generate different sequences? hopefully using LINQ

The problem is that you're creating a new instance of Random on each iteration. Each instance will be taking its initial seed from the current time, which changes relatively infrequently compared to how often your delegate is getting executed. You could create a single instance of Random and use it repeatedly. See my article on randomness for more details.

However, I would also suggest that you use a Fisher-Yates shuffle instead of OrderBy in order to shuffle the values (there are plenty of examples on Stack Overflow, such as this one)... although it looks like you're trying to bias the randomness somewhat. If you could give more details as to exactly what you're trying to do, we may be able to help more.

You are creating 10 instances of Random in quick succession, and pulling the first pseudo-random number from each of them. I'm not surprised they're all the same.

Try this:

Random r = new Random();
var sequence = Enumerable.Range(0, 9).OrderBy(n => n * n * r.Next());

In my code I use this static method I wrote many years ago, and it still shows good randomization:

using System.Security.Cryptography;
...

public static int GenerateRandomInt(int from, int to)
{
  byte[] salt = new byte[4];
  RandomNumberGenerator rng = RandomNumberGenerator.Create();
  rng.GetBytes(salt);
  int num = 0;
  for (int i = 0; i < 4; i++)
  {
    num += salt[i];
  }
  return num % (to + 1 - from) + from;
}

Can't explain this example in detail, I need to bring myself back in time to remember, but I don't care ;)