https://github.com/a13X-B/loaded_dice

Walker-Vose alias method for efficiently simulating a loaded die, written in lua
https://github.com/a13X-B/loaded_dice

Last synced: 9 days ago
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Walker-Vose alias method for efficiently simulating a loaded die, written in lua

• Host: GitHub
• URL: https://github.com/a13X-B/loaded_dice
• Owner: a13X-B
• License: unlicense
• Created: 2024-06-30T13:50:40.000Z (7 months ago)
• Default Branch: main
• Last Pushed: 2024-06-30T14:54:17.000Z (7 months ago)
• Last Synced: 2024-07-03T02:17:41.205Z (7 months ago)
• Language: Lua
• Size: 6.84 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

Awesome Lists containing this project

• awesome-love2d - loaded_dice - Walker-Vose alias method implementation (loaded dice-like RNG) useful for rolling loot tables, etc. (Math)

README

        
# loaded_dice

single file helper library that implements Walker-Vose alias method for efficiently simulating a loaded die

written in lua

useful for rolling loot tables, spinning roulettes with non-even sectors, damage distributed status effects, you name it

# api

import the library

`local ld = require("loaded_dice")`

## create a new loaded die

```lua

local die = ld.new_die()

```

creates a new loaded die

also can take a list of weights or a table as anargument

## add weights

```lua

die:add(weight)

```

add new weighted side to the die, weights are dimensionless and the probablility will be proportional to the total weights sum

## set weights

```lua

die:set(index, weight)

```

replace weight at existing index

## read weights

```lua

die:get(index)

```

returns previously set weight in case you forgot what it was

## generate a weighted random number

```lua

die:random(random1, random2)

```

can also use `die:sample(...)`

takes two random numbers in range `[0,1)` as parameters and returns a weighted random integer between 1 and number of added weights

`die:random()` with no parameters will use `math.random` internally

`die:random_fn(function)` will generate a random number using the provided function

`die:random_gen(rng, [name])` will generate a random number using provided `rng` object, will call it by name like `rng:name()` if provided and assumes `rng:random()` by default

## build alias table

```lua

die:build_alias()

```

the alias table will be built automatically if it's outdated at the time of calling `die:random`

this methods lets you build it manually

# example

```lua

local ld = require("loaded_dice")

local loot = {"dirt","leaf","stick","string","paperclip","copper coin"} -- possible loot

local weights = {50,30,30,10,7,2} -- drop weights, notice how they're specifically not percentages

local loot_die = ld.new_die(weights) -- new shiny loaded die

print(loot[loot_die:random()]) -- roll for loot! possible output: copper coin, lucky

```