dice-calc 0.3.5.dev1

Advanced Calculator for Dice

PythonDice

Try it online: https://ar-kareem.github.io/PythonDiceWeb/

This is a python package that includes a simple to use and powerful dice probability engine.

This package offers features and capabilities to calculate probabilities of arbitrary dice scripts including full capabilities of anydice.com.

Additionaly, this package includes the first* custom built compiler that translates any** valid anydice.com code into runnable python code.

This project is still in early development but everything mentioned above is complete. (project started October 2024)

* as far as we know

** except very rare edge cases (e.g. using numbers >$2^{53}$ causing anydice to potentially perform incorrect/different calculations) mentioned at the end for transparency.

Features

1. Ability to compile and run any anydice script directly and locally in python with a single function call.

   • Of course, this means that all operations and functions that are available in anydice are available in this package.

2. Ability to write scripts that combine the complexity of the anydice language with the power of Python (built-in libraries such as itertools, custom classes, etc.).

3. Very light-weight pure Python implementation with zero dependencies. Using this package requires no other modules.

4. Package is actively maintained (as of October 2024) and we welcome all new issues/questions/feedback/suggestions

Installation

pip install dice-calc

This package has no dependencies. Requires Python >= 3.9

Basic Usage

If you are familiar with the anydice.com language then you should skip to section compiling anydice.com code which automatically converts the provided anydice code to this packages code thus teaching you all the nuances of this package.

The examples below are not comprehensive at all. They just show very basic use cases of our package.

Example #1:

Let's roll a single d20 dice (a d20 is a regular twenty sided-die)

from dice_calc import roll, output
X = roll(20)
output(X)

10.5 ± 5.77
 1:  5.00  ████
 2:  5.00  ████
 3:  5.00  ████
 4:  5.00  ████
 5:  5.00  ████
 6:  5.00  ████
 7:  5.00  ████
 8:  5.00  ████
 9:  5.00  ████
10:  5.00  ████
11:  5.00  ████
12:  5.00  ████
13:  5.00  ████
14:  5.00  ████
15:  5.00  ████
16:  5.00  ████
17:  5.00  ████
18:  5.00  ████
19:  5.00  ████
20:  5.00  ████
----------------------------------------------------------------------------------------

The numbers on the first line are the mean and std.

Example #2

Let's roll two d6 dice (a d6 is a regular six sided-die)

from dice_calc import roll, output
X = roll(2, 6)  # or roll(6) + roll(6)
output(X)

7.0 ± 2.42
 2:  2.78  ██
 3:  5.56  ████
 4:  8.33  ██████
 5: 11.11  █████████
 6: 13.89  ███████████
 7: 16.67  █████████████
 8: 13.89  ███████████
 9: 11.11  █████████
10:  8.33  ██████
11:  5.56  ████
12:  2.78  ██
----------------------------------------------------------------------------------------

Example #3

What about rolling a D20 plus a D6?

from dice_calc import roll, output
X = roll(20) + roll(6)
output(X)

14.0 ± 6.01
 2:  0.83  █
 3:  1.67  █
 4:  2.50  ██
 5:  3.33  ███
 6:  4.17  ███
 7:  5.00  ████
 8:  5.00  ████
 9:  5.00  ████
10:  5.00  ████
11:  5.00  ████
12:  5.00  ████
13:  5.00  ████
14:  5.00  ████
15:  5.00  ████
16:  5.00  ████
17:  5.00  ████
18:  5.00  ████
19:  5.00  ████
20:  5.00  ████
21:  5.00  ████
22:  4.17  ███
23:  3.33  ███
24:  2.50  ██
25:  1.67  █
26:  0.83  █
----------------------------------------------------------------------------------------

Example #4

What about the probability distribution of rolling two D20's with advantage (i.e. rolling two D20's and taking the highest number)

from dice_calc import roll, output
X = 1 @ roll(2, 20)
output(X)

13.82 ± 4.71
 1:  0.25  
 2:  0.75  █
 3:  1.25  █
 4:  1.75  █
 5:  2.25  ██
 6:  2.75  ██
 7:  3.25  ███
 8:  3.75  ███
 9:  4.25  ███
10:  4.75  ████
11:  5.25  ████
12:  5.75  ████
13:  6.25  █████
14:  6.75  █████
15:  7.25  ██████
16:  7.75  ██████
17:  8.25  ██████
18:  8.75  ███████
19:  9.25  ███████
20:  9.75  ████████
----------------------------------------------------------------------------------------

Example #5

Let's try a slightly more complex example.

Rolling a D20 with advantage + two D6's + 5

from dice_calc import roll, output
D20_adv = 1 @ roll(2, 20)
two_D6 = roll(2, 6)
result = D20_adv + two_D6 + 5
output(result)

25.82 ± 5.29
 8:  0.01  
 9:  0.03  
10:  0.10  
11:  0.21  
12:  0.38  
13:  0.63  
14:  0.96  █
15:  1.35  █
16:  1.78  █
17:  2.26  ██
18:  2.75  ██
19:  3.25  ███
20:  3.75  ███
21:  4.25  ███
22:  4.75  ████
23:  5.25  ████
24:  5.75  ████
25:  6.25  █████
26:  6.75  █████
27:  7.25  ██████
28:  7.47  ██████
29:  7.38  ██████
30:  6.99  █████
31:  6.26  █████
32:  5.20  ████
33:  3.78  ███
34:  2.57  ██
35:  1.57  █
36:  0.80  █
37:  0.27  
----------------------------------------------------------------------------------------

getting evaluated results (roller)

Any RV object (dice / random variable) can be rolled using the rolled function.

from dice_calc import roll, roller
X = 1 @ roll(2, 20)  # rolls a d20 with advantage
roller(X)  # gets a random value from rolling a d20 with advantage

19

Complex Example:

Let's try calculating the total damage of the following attack on a boss in an RPG:

• TO HIT: 1d20 + 7 against 22 AC (less than 22 is a miss. rolling a 20 is a CRITICAL so double the damage die)
• DAMAGE: 2d8 + 4 blunt damange
• + 1d4 thunder damage
• + 1d10 + 3 radiant damange (half damage if the target succeeds a 16 DC wisdom saving throw, boss has +5 wis saving throw)

from dice_calc import roll, anydice_casting, T_N, T_S, T_D

# In anydice we have (:N, :S, and :D) which are (T_N, T_S, and T_D) in here
# read: https://anydice.com/docs/functions for more information
@anydice_casting()
def calculate(to_hit_roll: T_N, save_roll: T_N):  # type hinting as T_N REQUIRED!!!
    if to_hit_roll + 7 < 22:  # miss
        return 0
    is_crit = (to_hit_roll == 20)
    dmg_die_mult = 2 if is_crit else 1
    blung_dmg = roll(2 * dmg_die_mult, 8) + 4
    thund_dmg = roll(1 * dmg_die_mult, 4)
    radiant_dmg = roll(1 * dmg_die_mult, 10) + 3
    if save_roll + 5 >= 16:  # save success
        radiant_dmg = radiant_dmg // 2
    return blung_dmg + thund_dmg + radiant_dmg


X = calculate(roll(20), roll(20))

# plotting code
from matplotlib import pyplot as plt
vals, probs = zip(*X.get_vals_probs())
plt.bar(vals, probs); plt.xlabel('Damage'); plt.ylabel('Probability');

Notice how we used the decorator @anydice_casting to use if conditions on dice inside of a custom function. Typehinting the input to int is required, the engine knows that you want to calculate the function many times based on all possible combinations of the input random variable.

The three valid typehints that the decorator @anydice_casting looks for are : int, : Seq, : RV which are equivelant to the 3 types :n, :s, and :d respectively in anydice. The casting done by @anydice_casting is exactly how casting is done in the anydice language. For more info on that please read the documentation functions -> Parameter types in the anydice docs .

Note: Seq and RV are imported from dice_calc.randvar

Getting probabilities as dict

from dice_calc import roll
X = 1 @ roll(2, 20)  # D20 with advantage
pdf = dict(X.get_vals_probs())
print(pdf)

{1: 0.0025, 2: 0.0075, 3: 0.0125, 4: 0.0175, 5: 0.0225, 6: 0.0275, 7: 0.0325, 8: 0.0375, 9: 0.0425, 10: 0.0475, 11: 0.0525, 12: 0.0575, 13: 0.0625, 14: 0.0675, 15: 0.0725, 16: 0.0775, 17: 0.0825, 18: 0.0875, 19: 0.0925, 20: 0.0975}

plotting using matploblib

from dice_calc import roll
X = 1 @ roll(2, 20) + 8  # D20 with advantage + 8

# plotting code
from matplotlib import pyplot as plt
vals, probs = zip(*X.get_vals_probs())
percent = [p * 100 for p in probs]
plt.bar(vals, percent); plt.xlabel('Roll'); plt.ylabel('Probability %');

compiling anydice.com code

anydice is a powerful and popular online dice calculater which inspired the creation of this package. Any* valid code from anydice can be converted to valid python code using this package in a single function call.

Below we take an example piece of code from the anydice articles legend of the five rings.

We convert it using the function compile_anydice and then execute it using our package (p.s. don't forget to import all the library functions as we do below).

from dice_calc.parser import compile_anydice

EXAMPLE_CODE = """
function: convert SUM:n {
 if SUM >= 1000 {
  TENSROLLED: SUM / 1000
  result: SUM - TENSROLLED * 990 + TENSROLLED d [explode d10]
 }
 result: SUM
}

output [convert [highest 3 of 6d{1..9, 1000}]] named "6k3 exploded after keeping"
"""

code = compile_anydice(EXAMPLE_CODE)
print(code)

@anydice_casting()
def convert_X(SUM: T_N):
  if SUM >= 1000:
    TENSROLLED = SUM // 1000
    return SUM - TENSROLLED * 990 + roll(TENSROLLED, explode_X(roll(10)))
  
  return SUM

output(convert_X(highest_X_of_X(3, roll(6, get_seq([myrange(1, 9), 1000])))), named=f"6k3 exploded after keeping")

# IMPORT EVERYTHING
from dice_calc import *

# EXECUTE CODE FROM COMPILE_ANYDICE
@anydice_casting()
def convert_X(SUM: T_N):
  if SUM >= 1000:
    TENSROLLED = SUM // 1000
    return SUM - TENSROLLED * 990 + roll(TENSROLLED, explode_X(roll(10)))
  
  return SUM

output(convert_X(highest_X_of_X(3, roll(6, Seq([myrange(1, 9), 1000])))), named=f"6k3 exploded after keeping")

6k3 exploded after keeping 26.53 ± 8.32
  3:  0.00  
  4:  0.00  
  5:  0.00  
  6:  0.01  
  7:  0.02  
  8:  0.04  
  9:  0.09  
 10:  0.17  
 11:  0.29  
 12:  0.48  
 13:  0.76  █
 14:  1.12  █
 15:  1.62  █
 16:  2.22  ██
 17:  2.92  ██
 18:  3.71  ███
 19:  4.55  ████
 20:  5.31  ████
 21:  6.00  █████
 22:  6.40  █████
 23:  6.51  █████
 24:  6.20  █████
 25:  5.61  ████
 26:  4.65  ████
 27:  3.78  ███
 28:  3.14  ██
 29:  3.45  ███
 30:  3.40  ███
 31:  3.32  ███
 32:  3.16  ██
 33:  2.93  ██
 34:  2.60  ██
 35:  2.21  ██
 36:  1.78  █
... output cropped ...

Or you can do it all in one line

from dice_calc.parser import compile_anydice, _get_lib

EXAMPLE_CODE = """
function: convert SUM:n {
 if SUM >= 1000 {
  TENSROLLED: SUM / 1000
  result: SUM - TENSROLLED * 990 + TENSROLLED d [explode d10]
 }
 result: SUM
}

output [convert [highest 3 of 6d{1..9, 1000}]] named "6k3 exploded after keeping"
"""

exec(compile_anydice(EXAMPLE_CODE), _get_lib())

6k3 exploded after keeping 26.53 ± 8.32
  3:  0.00  
  4:  0.00  
  5:  0.00  
  6:  0.01  
  7:  0.02  
  8:  0.04  
  9:  0.09  
 10:  0.17  
 11:  0.29  
 12:  0.48  
 13:  0.76  █
 14:  1.12  █
 15:  1.62  █
 16:  2.22  ██
 17:  2.92  ██
 18:  3.71  ███
 19:  4.55  ████
 20:  5.31  ████
 21:  6.00  █████
 22:  6.40  █████
 23:  6.51  █████
 24:  6.20  █████
 25:  5.61  ████
 26:  4.65  ████
 27:  3.78  ███
 28:  3.14  ██
 29:  3.45  ███
 30:  3.40  ███
 31:  3.32  ███
 32:  3.16  ██
 33:  2.93  ██
 34:  2.60  ██
 35:  2.21  ██
 36:  1.78  █
... output cropped ...

Note that calls to the built-in python function exec executes arbitrary code and could be dangerous if malicious code is run. Only run exec on code you trust.

compile_anydice was developed to only generate safe code, but no garuntees are made.

compile_anydice edge cases

The compile_anydice function was a large part of this project. Under the hood it is a custom compiler built using Python's implementation of lex and yacc provided by PLY (Python Lex-Yacc).

As far as we tested, almost all valid anydice code worked perfectly using our compiler, except for extremely rare/intentionally ignored subsets of anydice code mentioned below:

1. certain operators on ints and nothing else. Update : #1 has been correctly implemented (as an optional compiler flag)

2. Limit on global function depth. Update : #2 has been correctly implemented

3. (very rare) Naming a fucntion as an illegal reserved keywords Update : #3 been correctly implemented ; automatically turns on when a collision is detected by the compiler

4. (very rare) MAX_INT is higher in python than in JavaScript: This is a very rare issue when a number is larger than $2^{53}$. See example we made here: https://anydice.com/program/39567

Note: that in some cases our compile_anydice code runs while anydice crashes. This is because our compiler allows certain pieces of code (like defining functions within functions or outputs inside of functions) to execute perfectly while anydice crashes. We do not consider this as a failiure since our goal is to make any code that runs on anydice to also run using our package, the reverse of that is of no concern. In fact, the descrepancy is considered a positive for us as it means we handle more pieces of code than anydice.

If you discover any code that behaves differently when run on anydice.com then please report it to us as an issue so we can keep improving this package.