Probability of an event occurring when represented as whole numbers in percentage form

Question

Probability of an event occurring when represented as whole numbers in percentage form

Currently, I'm developing a unique job system within a Discord bot that allows users to mine various types of ores. The probability of receiving specific ores is based on the user's mining skill level, which is stored in a database and can vary accordingly. For example, at Skill Level 1, the chances are as follows:

let coal_chance = 80
let copper_chance = 15
let iron_chance = 5
let gold_chance = 0
let diamond_chance = 0
let emerald_chance = 0

Conversely, at Skill Level 2, the distribution changes:

let coal_chance = 50
let copper_chance = 35
let iron_chance = 10
let gold_chance = 5
let diamond_chance = 0
let emerald_chance = 0

This pattern continues for higher skill levels. However, my current dilemma lies in creating a dynamic chance system based on these percentages.

I initially attempted to implement a solution using Math.Random() alongside a series of if statements. Unfortunately, this approach proved inefficient since it required separate conditionals for each skill level. Furthermore, any adjustments made to the ore probabilities within the database would necessitate corresponding alterations to the codebase.

javascript typescript discord.js

Answer 1

Answer №1

After seeing a suggestion from @sudheeshix, I devised this makeshift solution:

const cumulativeChances = [ 
  {c: 100, i: "coal"},
  {c: 50, i: "copper"},
  {c: 15, i: "iron"},
  {c: 5, i: "gold"},
  {c: 0, i: "emerald"},
  {c: 0, i: "diamond"}
]
const mineOre = () => {
  let rng = Math.random() * 100
  let won = 'coal'
  for (item of cumulativeChances) {
    if (item.c < rng) break
    won = item.i
  }
  return won
}

// Testing if it works as intended
const calculatedChances = {
  coal: 0,
  copper: 0,
  iron: 0,
  gold: 0,
  emerald: 0,
  diamond: 0
}
let tries = i = 10000;
while(i--) {
  let won = mineOre()
  calculatedChances[won] += (1 / tries * 100)
}
console.log(calculatedChances)

While there may be areas for enhancement, this concept offers a starting point. Happy coding :)

Answer 2

After seeing a suggestion from @sudheeshix, I devised this makeshift solution:

const cumulativeChances = [ 
  {c: 100, i: "coal"},
  {c: 50, i: "copper"},
  {c: 15, i: "iron"},
  {c: 5, i: "gold"},
  {c: 0, i: "emerald"},
  {c: 0, i: "diamond"}
]
const mineOre = () => {
  let rng = Math.random() * 100
  let won = 'coal'
  for (item of cumulativeChances) {
    if (item.c < rng) break
    won = item.i
  }
  return won
}

// Testing if it works as intended
const calculatedChances = {
  coal: 0,
  copper: 0,
  iron: 0,
  gold: 0,
  emerald: 0,
  diamond: 0
}
let tries = i = 10000;
while(i--) {
  let won = mineOre()
  calculatedChances[won] += (1 / tries * 100)
}
console.log(calculatedChances)

While there may be areas for enhancement, this concept offers a starting point. Happy coding :)

Answer 3

Answer №2

Let's explore a different approach:

First, transform your resource values into an array:

resources = ["silver", "bronze", "steel", "titanium", "platinum", "sapphire"];
chances = [70, 10, 15, 5, 0, 0];

Next, calculate cumulative sums of the percentages, following the method described in this response.

const cumulativeSum = (sum => value => sum += value/100)(0);
cum_chances = chances.map(cumulativeSum);

The division by 100 is necessary to obtain float values since Math.random() generates numbers between 0 and 1. Using the chances values above, cum_chances would be [0.7, 0.8, 0.95, 1, 1, 1].

Now, generate a random probability.

random_prob = Math.random();

Then, determine the index of the first element in the array where random_prob fits using the guidance provided in this suggestion.

idx = cum_chances.findIndex(function (el) {
    return el >= random_prob;
});
resource_found = resources[idx];

For instance, if random_prob equals 0.85, this process will yield an index of 2, resulting in resources[idx] returning "steel".

Answer 4

Let's explore a different approach:

First, transform your resource values into an array:

resources = ["silver", "bronze", "steel", "titanium", "platinum", "sapphire"];
chances = [70, 10, 15, 5, 0, 0];

Next, calculate cumulative sums of the percentages, following the method described in this response.

const cumulativeSum = (sum => value => sum += value/100)(0);
cum_chances = chances.map(cumulativeSum);

The division by 100 is necessary to obtain float values since Math.random() generates numbers between 0 and 1. Using the chances values above, cum_chances would be [0.7, 0.8, 0.95, 1, 1, 1].

Now, generate a random probability.

random_prob = Math.random();

Then, determine the index of the first element in the array where random_prob fits using the guidance provided in this suggestion.

idx = cum_chances.findIndex(function (el) {
    return el >= random_prob;
});
resource_found = resources[idx];

For instance, if random_prob equals 0.85, this process will yield an index of 2, resulting in resources[idx] returning "steel".

Probability of an event occurring when represented as whole numbers in percentage form

Answer №1

Answer №2

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