weighted boolean value - scaling

Question

I am not sure how to implement this, but here is the description:

Take a number as input in between the range 0-10 (0 always returning false, 10 always returning true)
Take the argument which was received as input, and pass into a function, determining at runtime whether the boolean value required will be true or false

Say for example:

Input number 7 -> (7 has a 70% chance of generating a true boolean value) -> pass into function, get the boolean value generated from the function.

This function will be run multiple times - perhaps over 1000 times.

Thanks for the help, I appreciate it.

What have you tried so far? If you don't know where to begin I'd start with this question: http://stackoverflow.com/questions/9471604/what-is-the-best-way-to-generate-random-numbers — Mark Ransom, Jun 07 '13 at 22:28

score 4 · Accepted Answer · answered Jun 07 '13 at 22:27

4

bool func(int v) {
  float f = rand()*1.0f/RAND_MAX;
  float vv= v / 10.0f;
  return f < vv;
}

answered Jun 07 '13 at 22:27

perreal

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score 0 · Answer 2 · answered Jun 07 '13 at 22:28

0

I would say generate a random number representing a percentage (say 1 to 100) then if the random number is less then or equal to the percentage chance mark it as true, else mark it as false.

answered Jun 07 '13 at 22:28

MichelleJS

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coolcoolcool · Answer 3 · 2017-06-20T22:28:05.440

0

Here's an idea , I'm not sure that's it's gonna be helpful;

bool randomChoice(int number){
    int result =rand() % 10;
    return number>=result;

    }

Hope it's helpful

edited Jun 20 '17 at 22:28

answered Jun 07 '13 at 22:30

coolcoolcool

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you've got some extra braces there. Also `if (number>=result) return true; else return false;` is a bit of an anti-pattern. Just `return (number>=result); ` Oh, and which `random()` function are you calling? The stdlib one doesn't take an argument http://linux.die.net/man/3/random – John Carter Jun 07 '13 at 22:34
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Ack, **don't** call `srand` every time you call `rand`. Call it **once only**. – Pete Becker Jun 07 '13 at 23:20
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Yeah, reseeding the random number to the current time on every call is a fantastic way to make your numbers not at all random. – John Carter Jun 08 '13 at 00:31

score 0 · Answer 4 · answered Jun 07 '13 at 22:34

This is an interesting question! Here's what I think you should do, in pseudo code:

boolean[] booleans = new boolean[10]; //boolean array of length 10

function generateBooleans(){
    loop from i = 0 to 10:
        int r = random(10);    //random number between 0 and 9, inclusive
        if(r < i){
            booleans[i] = true;
        }
    }
}

You can then compare the user's input to your boolean array to get the pre-determined boolean value:

boolean isTrue = booleans[userInputNumber]

weighted boolean value - scaling

4 Answers4