Random Number Not in Sequence

[mshmyob]

I know how to create a random number using lower and upper limits but am curious if you can generate a random number from a set of specific numbers.

For instance I want to randomly pick either 1, 3, 7, or 9 only.

Right now I just put the random number generator with a lower limit of 1 and an upper limit of 9 in a loop until it generates one of the above numbers.

I was wondering if there was a simple formula like (this is the standard upper limit lower limit formula)

vLoop = Int((9 - 1 + 1) * Rnd + 1)

[ADezii]

I know how to create a random number using lower and upper limits but am curious if you can generate a random number from a set of specific numbers.

For instance I want to randomly pick either 1, 3, 7, or 9 only.

Right now I just put the random number generator with a lower limit of 1 and an upper limit of 9 in a loop until it generates one of the above numbers.

I was wondering if there was a simple formula like (this is the standard upper limit lower limit formula)

vLoop = Int((9 - 1 + 1) * Rnd + 1)

The following code will generate a Random 1, 3, 7, or 9. I also list a sample display of 25 Random Generations for the 4 specific numbers. Hope this helps:

'Dimension an Array = the number of Elements
Dim aintRndNums(1 To 4) As Integer, intRandomIndex As Integer
 
'Assign the numbers to specific Indexes
aintRndNums(1) = 1
aintRndNums(2) = 3
aintRndNums(3) = 7
aintRndNums(4) = 9
 
Randomize        'seed the Random Number Generator
 
'Grab a Random Index between 1 and 4
intRandomIndex = Int(Rnd * UBound(aintRndNums()) + 1)
 
'And your Random Number is (1, 3, 7, or 9)
Debug.Print "Random Number: " & aintRndNums(intRandomIndex)
 

Sample OUTPUT:

Random Number: 7
Random Number: 3
Random Number: 9
Random Number: 3
Random Number: 1
Random Number: 7
Random Number: 7
Random Number: 9
Random Number: 3
Random Number: 1
Random Number: 9
Random Number: 1
Random Number: 9
Random Number: 1
Random Number: 3
Random Number: 1
Random Number: 7
Random Number: 3
Random Number: 1
Random Number: 9
Random Number: 1
Random Number: 1
Random Number: 3
Random Number: 1
Random Number: 7

P.S. - All the above boils down to: sequentially placing the numbers you wish to choose at Random into an Array, selecting a Random Index into the Array, and listing the value at that Index.

[mshmyob]

Very interesting way of doing it. With a minor change I can dynamically modify my random numbers.

The following code will generate a Random 1, 3, 7, or 9. I also list a sample display of 25 Random Generations for the 4 specific numbers. Hope this helps:

'Dimension an Array = the number of Elements
Dim aintRndNums(1 To 4) As Integer, intRandomIndex As Integer
 
'Assign the numbers to specific Indexes
aintRndNums(1) = 1
aintRndNums(2) = 3
aintRndNums(3) = 7
aintRndNums(4) = 9
 
Randomize        'seed the Random Number Generator
 
'Grab a Random Index between 1 and 4
intRandomIndex = Int(Rnd * UBound(aintRndNums()) + 1)
 
'And your Random Number is (1, 3, 7, or 9)
Debug.Print "Random Number: " & aintRndNums(intRandomIndex)
 

Sample OUTPUT:

Random Number: 7
Random Number: 3
Random Number: 9
Random Number: 3
Random Number: 1
Random Number: 7
Random Number: 7
Random Number: 9
Random Number: 3
Random Number: 1
Random Number: 9
Random Number: 1
Random Number: 9
Random Number: 1
Random Number: 3
Random Number: 1
Random Number: 7
Random Number: 3
Random Number: 1
Random Number: 9
Random Number: 1
Random Number: 1
Random Number: 3
Random Number: 1
Random Number: 7

P.S. - All the above boils down to: sequentially placing the numbers you wish to choose at Random into an Array, selecting a Random Index into the Array, and listing the value at that Index.

[ADezii]

Very interesting way of doing it. With a minor change I can dynamically modify my random numbers.

It is very adaptable, the numbers you select for Random Generation can be entered into a Table, you can enter as many as you like, and the code will do the rest with slight modification. This simple demo has you manually entering the valuers into an Array, this need not be the case.

[NeoPa]

In fact, any definable way of mapping the numbers can be used. In your case for instance, you could get a random number between 1 & 4, then multiply by 2 and subtract 1.
If there's a formula for it, it can be done.

[mshmyob]

I like the way Dezi did it. Storing previous results or new numbers in a table for future reference is something I may be able to use.

As you may have seen in my previous posts I am creating numerous learning type games (math, speling etc.) for my 7 yr old. And I also wanted to just create a simple game for her so I created a Tic Tac Toe game. So it is my first AI type program. It worked out very well and I put in 3 levels of difficulty.

I am now expanding the Tic Tac Toe game to a connect 4 type game but it allows the user to generate any size grid .

I think with the way Dezi did it I can create a system that allows the computer to actually learn.

[NeoPa]

I like the way Dezi did it. ...

So do I. So do I.
I was merely expanding on the possibilities of the concept. Had ADezii suggested the algorithmic approach, I would have mentioned the array one. Each has its pros and cons. The array approach is generally more flexible but can take more resource. Nowadays that's barely an issue of course.

[mshmyob]

I understood what you were pointing out and I did appreciate it. Your way would also work for me and I see that both have merits and are useful in different situations.

I like to see the different ways people come up with a solution to a problem, it gets me thinking on different paths.

For instance when I created the Tic Tac Toe game I did it without checking out any other code. After I got it to work I went online and checked how other people did it and found I did it in a very unique way. Almost all people used a 2 dimensional array but I used a 1 dimensional array and assigned each column, row and diagonal to the array. I worked out a simple formula of either adding or subtracting 1 from the number in the array (all started at 0). When a value either reached -3 or +3 that determined whether O or X won and also determined where the computer's next move should always be. But I also appreciated the 2 dimensional array method although it seemed more processor intensive (not that it would make much difference like you pointed out ).

I always appreciate everybody's input as long as they are constructive. And you guys always get me thinking (don't want the old grey matter to dry up).

So do I. So do I.
I was merely expanding on the possibilities of the concept. Had ADezii suggested the algorithmic approach, I would have mentioned the array one. Each has its pros and cons. The array approach is generally more flexible but can take more resource. Nowadays that's barely an issue of course.