Random Number Help

[johnny32190]

ok so im trying to make some easy AI

as the user clicks random buttons the program will keep a running tally of what they choose and then devide it by the amount of times that they have choosen.. thus the program will generate a percent of what he has choosen

now the hard part...
any one know how i can take these percentages and ask the computer to pull a random number using these percentages ... thus having a better chance of choosing something the impooter would have choosen

[SammyB]

Let's take a specific case and see how to do it.
Say we have three buttons
1 is pressed 30% of the time
2 is pressed 50% of the time
3 is pressed 20% of the time

So, if we generate a random number between 0 and 100, then
if the number is between 0 and 30, press 1
if the number is between 30 and 80, press 2
if the number is between 80 and 100, press 3

Make sense?

[Killer42]

Nice one, Sammy.

Note though, this may require some fairly sophisticated coding. (Hm, sounds like a good topic for a sample in the Articles area). What you need to be wary of, johnny, is just incorrectly "stacking" the percentages. A fairly common method of doing something a certain percentage of the time is like this...

• Generate a random number between, say, 0 and 100.
• If the number is <= my percentage, then we have a hit.

This works just fine. But in a case like this where you are choosing between a number of options, the natural inclination might be somethinbg like this (using Sammy's example)...

• Generate a random number between 0 and 100.
• If the number is <= 30, press 1
• Generate a random number between 0 and 100.
• If the number is <= 50, press 2
• Generate a random number between 0 and 100.
• If the number is <= 20, press 3

It may seem as though this would do what you want. But in fact this would change the probabilities quite significantly. For instance, this only allows something like (my math may be wrong) a 35% chance of generating a "2". And if I'm not mistaken, a 7% chance of producing a "3". (I don't have much confidence in my numbers, but hopefully you get the idea.)

So, just be aware of this pitfall.

[johnny32190]

thanks guys... im pretty sure i can figure the rest out from here

[Killer42]

thanks guys... im pretty sure i can figure the rest out from here

Glad we could help. :)

Let us know how it turns out.