ICM Calculator

Calculate ICM equities for poker tournament payouts.

Installation

Add @poker-apprentice/icm-calculator as a dependency.

• yarn:

  yarn add @poker-apprentice/icm-calculator

• npm:

  npm install @poker-apprentice/icm-calculator --save

Usage

This package exports a calculate function that can be used to calculate ICM payouts for a poker tournament based upon prize values and remaining chip stacks. To use it, simply pass an object containing numeric arrays of payouts values and chipStacks values.

calculateExact

The calculateExact function is based upon the Malmuth-Harville equation in section 2.2 of this article from the Journal of the Mathematical Society of the Philippines. Because calculateExact becomes exponentially more expensive as the size of chipStacks grows, it is not recommended to utilize this function beyond a small sampling.

This implementation in inspired by gpratte/icm-calculator.

import { calculateExact } from '@poker-apprentice/icm-calculator';

const icmAmounts = calculateExact({
  payouts: [425, 280, 130, 75],
  chipStacks: [150000, 98750, 45500, 13250],
});
console.log(icmAmounts); // => [323.2, 278.12, 195.79, 112.89]

calculateEstimate

The calculateEstimate function performs a Monte Carlo simulation (i.e.: random sampling) to come up with an acceptable approximate ICM calculation. This is based upon the ICM equities algorithm proposed by Tysen Streib on the 2+2 forums.

For larger data sets represented by chipStacks, the calculateEstimate function is recommended over calculateExact for time-sensitive implementations.

import { calculateEstimate } from '@poker-apprentice/icm-calculator';

const icmAmounts = calculateEstimate({
  payouts: [425, 280, 130, 75],
  chipStacks: [150000, 98750, 45500, 13250],
});
console.log(icmAmounts); // => [323.2, 278.12, 195.79, 112.89]

Optionally, an iterations option can be provided to override the default value of 10,000. This value specifies how many Monte Carlo simulations should be performed per the number of chip stacks provided in chipStacks. (For example, if chipsStacks is set to [1000, 500] and iterations is set to 10, then 2×10=20 total calculations will be performed.)

import { calculateEstimate } from '@poker-apprentice/icm-calculator';

const icmAmounts = calculateEstimate({
  payouts: [425, 280, 130, 75],
  chipStacks: [150000, 98750, 45500, 13250],
  iterations: 250,
});
console.log(icmAmounts); // => [323.2, 278.12, 195.79, 112.89]

calculate

The calculate function delegates to either calculateExact or calculateEstimate based upon the number of chipStacks provided.

import { calculate } from '@poker-apprentice/icm-calculator';

const icmAmounts = calculate({
  payouts: [425, 280, 130, 75],
  chipStacks: [150000, 98750, 45500, 13250],
});
console.log(icmAmounts); // => [323.2, 278.12, 195.79, 112.89]

Optionally, a threshold option can be provided to override the default value of 5. This value specifies whether the calculateExact or calculateEstimate function will be utilized based upon the size of chipStacks.

Contributing

If you'd like to fix a bug, add a feature, improve the documentation, or anything else to better this library, pull requests are welcomed!

1. Clone the repository:

   git clone git@github.com:poker-apprentice/icm-calculator.git

2. Install dependencies:

   yarn install

3. Include tests for your changes, and open a pull request.

If you are interested in contributing, but you are stuck or lost at any point in your efforts, please reach out for help!