Picking Number from List of Numbers

Unity Engine
1

Hello

I’m trying to make a basic card matching game, and I’m making a basic AI for the game. I need the AI to pick from a list of 16 cards. However after cards get removed my AI is still searching for them.CardPicker = Random.Range (1, 16);

That’s what i’m using. So the AI will keep on looking for cards until it finds the one’s left. Which takes awhile when there is only two cards left to find. Is there a random way to pick from a list of values. Such as (1,2,3,4,5,6,7 and so on) so when a card is removed I can remove one of the numbers?

2

This is untested code, but here’s the gist:

using System.Collections.Generic;

...

List<int> CardPicker;

// This will make a list of all cards
void MakeList()
{
    CardPicker = new List<int>();
    for (int i = 1; i <= 16; ++i)
    {
        CardPicker.Add(i);
    }
}

// This will return a random card that hasn't been used yet
int RandomCard()
{
    // Return a bad card if the list wasn't made yet
    if (CardPicker == null) return -1;

    // Return a bad card if the list is already empty
    if (CardPicker.Count <= 0) return -1;

    // Return a random card that's left and remove it so we don't pick it again
    int PickedCardIndex = Random.Range(0, CardPicker.Count);
    int PickedCard = CardPicker[PickedCardIndex];
    CardPicker.RemoveAt(PickedCardIndex);
    return PickedCard;
}
1 Like
3

You should try implementing Gambit’s method before asking people to just do it for you.

4

Another way you can do this is to randomize your list using linq. Consider this example here.
http://www.ookii.org/Blog/randomizing_a_list_with_linq

Once your list is randomized, you’ll just loop through it picking the first card, then the second, then the third. etc. Since the list will be random, it will still appear you’re picking a random card from the list each time, but you don’t have to loop through it trying to hit that one card you hadn’t picked. Nor do you have to remove stuff from the list. You can just randomize it again when you want to.

Just remember you’ll have to add using System.Linq;
And you’ll need to declare your random as
System.Random rnd = new System.Random(); or else it will try to use unity’s random instead.

And here, to add how you might do it slightly modified

List<int> myList = new List<int>();
        for(int x = 1;x < 16;x++)
        {
            myList.Add(x);
        }

        System.Random rnd = new System.Random();
        var randomizedList = (from item in myList
                              orderby rnd.Next()
                              select item).ToList<int>();

        print(randomizedList[0]);
2 Likes
5

Thank you I think I got it, sorta. But i’ll get it. I’ve spent a few hours on it but i’m getting there. So thanks :smile:

6

Thank you that’s another genius idea,