C# Random.Range

Hi,

Is it possible to use function System.Random.Range(i, list.length) ?

When I type System.Random I cannot access Range.

I would like just to shuffle items in a list similar to this:

for (int i = 0; i /span> alpha.Count; i++) {
string temp = alpha[i];
int randomIndex = Random.Range(i, alpha.Count);
alpha[i] = alpha[randomIndex];
alpha[randomIndex] = temp;
}

Thanks,

Petras

Replies to This Discussion

Permalink Reply by David Rutten on September 15, 2015 at 5:46am

Where did you find a method called Range on the Random class? I can't see it on the MSDN documentation.

Permalink Reply by Petras Vestartas on September 15, 2015 at 6:11am

It looks like I was looking at a wrong place.

Could you help me to shuffle objects in a list?

Thanks,

Petras

Permalink Reply by David Rutten on September 15, 2015 at 7:16am

I usually create an array of doubles and then sort that array while also sorting the other collection. But you'd have to convert the list to an array first.

Top of my head:

public void ShuffleList<T>(List<T> list, int seed)

{

T[] array0 = list.ToArray();

double[] array1 = new double[list.Count];

Random random = new Random(seed);

for (int i = 0; i < array1.Length; i++)

array[i] = random.NextDouble();

System.Array.Sort(ref array1, ref array0);

list.Clear();

list.AddRange(array0);

}

Permalink Reply by peter fotiadis on September 15, 2015 at 7:39am

Make chaos, take chaos ... whatever comes first.

he he

Attachments:

random_List_make_take.gh, 118 KB

Permalink Reply by Petras Vestartas on September 16, 2015 at 3:40pm

Dear David and Peter,

Thank you for the help for the chaos:)

Just one more question. How does this line work?

data.OrderBy(x => rnd.Next()).ToList();

Permalink Reply by peter fotiadis on September 16, 2015 at 11:52pm

This is a LINQ (Google that) thingy (kinda a "SQL" (kinda) type of "language"):

https://msdn.microsoft.com/en-us/library/vstudio/bb534966%28v=vs.10...

For instance if you want to find things that (a) are objects, (b) of type slider, (c) where their nickname starts with ... er ... "LordOfDarkness" and (d) put them into a List you type the following:

BTW: LINQ may be cool but is slow.

BTW: Since you are after chaos ... what about adding chaos to chaos? See attached.

Attachments:

Dice_on_trees_V1.gh, 127 KB

Permalink Reply by peter fotiadis on September 17, 2015 at 12:05am

LINQ is rather a handy way to create "expressions" for handling collections (but slow). See this (a bit more complex, NOT related with chaos - just a LINQ demo, he he) portion of some code that does ... er ... something:

Permalink Reply by peter fotiadis on September 17, 2015 at 12:36am

BTW: Get this all-time-classic LINQ stuff from The Master Of All C# things.

Attachments:

101 LINQ Samples.zip, 1.7 MB

Permalink Reply by Petras Vestartas on September 17, 2015 at 12:38am

Thanks for the information. Is this procedure slower than David Rutten script?

Permalink Reply by Vicente Soler on September 17, 2015 at 1:37am

Both Array.Sort and OrderBy will probably end up using quicksort (depending on the number of elements). If you really care about performance, use the Fisher–Yates shuffle (https://en.m.wikipedia.org/wiki/Knuth_shuffle) where you go through the list just once.
Doesn't make sense to care about the speed of linq if you're using a slow algoritm.

Permalink Reply by peter fotiadis on September 17, 2015 at 3:52am

Make chaos, take chaos, skin a cat with 3 ways ... whatever comes first.

Attachments: