A crate for calculating distrete probability distributions of dice.
To create a [Dice], build it from a [DiceBuilder] or directly from a string:
let dice: Dice = DiceBuilder::from_string("2d6").unwrap().build()
let dice: Dice = Dice::build_from_string("2d6").unwrap()
Properties of these dice are calculated in the build() function:
min: 2
max: 12
mode: vec![7],
mean: 7,
median: 7,
distribution: vec![(2, 1/36), (3, 1/18), (4, 1/12), (5, 1/9), (5, 1/9), (6, 5/36), (7, 1/6), ...]
cumulative_distribution: vec![(2, 1/36), (3, 1/12), (4, 1/6), ...]
A DiceBuildingError could be returned, if the input string could not be parsed into a proper syntax tree for the [DiceBuilder].
To roll a [Dice] call the roll() function:
let num = dice.roll();
// num will be some i64 between 2 and 12, sampled according to the dices distribution
For rolling multiple times call the roll_multiple() function:
let nums = dice.roll_multiple(10);
// nums could be vec![7,3,9,11,7,8,5,6,3,6]
Some exaple strings that can be passed into the DiceBuilder::from_string(input) function
3 six-sided dice:
txt
"3d6", "3w6" or "3xw6"
one six-sided die multiplied by 3:
txt
"3*d6" or "d6*3"
rolling one or two six sided dice and summing them up
txt
"d2xd6"
the maximum of two six-sided-dice minus the minimum of two six sided dice
txt
"max(d6,d6)-min(d6,d6)""
rolling a die but any value below 2 becomes 2 and above 5 becomes 5
txt
"min(max(2,d6),5)"
multiplying 3 20-sided-dice
txt
"d20*d20*d20"
This [crate] uses the BigFraction data type from the fraction crate to represent probabilities
This is quite nice because it allows for precise probabilities with infinite precision.
The drawback is that it is less efficient than using floats.
While "d100*d100" takes about 100ms for me, something like "d10xd100" took 9.000 ms to finish calculating the probability distribution.
There is room for optimization.