dwyl / dwyl/learn-javascript

Random Number Generator "Randomness" Check?

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enhancement question
Dominant language
HTML
Stars
65
Forks
15
PR merge metrics
No merged PRs in 30d

Description

Given the following "Random Integer between range X and Y" function:

``` js
/**
* Returns a random integer between min (inclusive) and max (inclusive)
* Using Math.round() will give you a non-uniform distribution!
* from: http://stackoverflow.com/a/1527820/1148249
*/
function get_random_int(min, max) {
return Math.floor(Math.random() * (max - min + 1)) + min;
}
```

We can run the following test to confirm the randomness:

``` js
var i = 0; // counter for looping.
var results = {}; // store the results of running get_random_int
var min = 0;
var max = 9;
for(i = min; i <= max; i++) {
results[i] = 0; // initialize results to zero;
}
i = 0; // reset/reuse i counter.
var test_count = 10000000;
while(i < test_count) {
var r = get_random_int(min, max);
results[r]++; // increment the count for a given random number
i++;
}
Object.keys(results).forEach(function(k) {
results[k] = results[k].toString() + ' > ' + (results[k] / test_count * 100).toFixed(3) + ' %';
});
console.log(JSON.stringify(results, null, 2));
```

Which outputs:

``` js
{
"0": "1000900 > 10.009 %",
"1": "999727 > 9.997 %",
"2": "999742 > 9.997 %",
"3": "999268 > 9.993 %",
"4": "1000650 > 10.007 %",
"5": "998621 > 9.986 %",
"6": "1000241 > 10.002 %",
"7": "1000716 > 10.007 %",
"8": "1000151 > 10.002 %",
"9": "999984 > 10.000 %"
}
```

Which is a pretty decent distribution...

Contributor guide

No contributing guide indexed for this repository

Research direction

Start by locating the get_random_int function in the repository and run the JavaScript loop shown in the issue with the stated range and test count. The issue does not identify a file, test location, or requested repository change; clarify whether the distribution check should be added or documented before defining what done means.

Written by the indexing model from the issue text.

Assessment

Tech stack
javascript
Domain
testing
Issue type
Feature
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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