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https://github.com/poker-apprentice/hand-evaluator

Evaluate the strength of a hand of poker
https://github.com/poker-apprentice/hand-evaluator

omaha omaha-poker plo poker poker-cards poker-hands texas-holdem texas-holdem-poker texasholdem texasholdemhandevaluator

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Evaluate the strength of a hand of poker

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README 

        
# Poker Hand Evaluator



A collection of useful functions for determining the strongest possible hand given a coordination of cards (hole cards & community cards), the strongest effective hand when comparing two hands, and the probability of winning the hand given what cards are known.



## Usage



### Types



The following types are defined & utilized by this package.



- `EvaluatedHand`: An object representing the effective hand & strength, given a coordination of cards.

- `Odds`: An object representing how a hand will perform given a scenario. Includes the number of `wins`, `ties`, and `total` possible outcomes.



### Core Functions



#### `evaluate`



Given a list of hole cards and (optionally) community cards, determine the best possible poker hand and the strength of that hand.



```ts

import { evaluate } from '@poker-apprentice/hand-evaluator';

import { HandStrength } from '@poker-apprentice/types';



const result = evaluate({

  holeCards: ['As', 'Qd'],

  communityCard: ['Js', 'Kc', 'Td'],

});



console.log(result);

// => { hand: ['As', 'Kc', 'Qd', 'Js', 'Td'], strength: 6 };



console.log(result.strength === HandStrength.Straight);

// => true

```



Note that the `evaluate` does not require 5 cards to determine the best hand. The best hand possible with fewer cards or more cards can be determined as well.



```ts

console.log(evaluate({ holeCards: ['As', 'Ad'] }));

// => { hand: ['As', 'Ad'], strength: 9 };



console.log(

  evaluate({

    holeCards: ['9s', '8s'],

    communityCards: ['5d', '6d', '6c', '7c', '2h'],

  }),

);

// => { hand: ['9s', '8s', '7c', '6d', '5d'], strength: 6 };

```



By default, the `evaluate` function allows any number of hole cards or community cards to be used when determining the best possible poker hand. If a specific number of hole cards must be used (e.g.: exactly 2 cards in Omaha or up to 2 cards in Pineapple), then the `minimumHoleCards` and `maximumHoleCards` options can be provided.



```ts

const omahaHand = evaluate({

  holeCards: ['As', 'Kd', 'Td', '2s'],

  communityCards: ['Js', '4s', '3d', '5d', 'Ah'],

  minimumHoleCards: 2,

  maximumHoleCards: 2,

});

console.log(omahaHand);

// => { hand: ['5d', '4s', '3d', '2s', 'As'], strength: 6 }



const pineappleHand = evaluate({

  holeCards: ['Jc', 'Tc', '7d'],

  communityCards: ['9h', '8c', '2d'],

  maximumHoleCards: 2,

});

console.log(pineappleHand);

// => { hand: ['Jc', 'Tc', '9h', '8c', '2d'], strength: 10 }

```



#### `compare`



Given two evaluated hands, returns -1, 0, or 1 to represent the stronger hand.



```ts

import { compare, evaluate } from '@poker-apprentice/hand-evaluator';



const hand1 = evaluate({ holeCards: ['9s', '8s', '5d', '6d', '6c', '7c', '2h'] });

const hand2 = evaluate({ holeCards: [] });

const result = compare(hand1, hand2);



console.log(result);

// => -1

```



This function can be used to sort any number of hands in an array.



```ts

import { compare, evaluate } from '@poker-apprentice/hand-evaluator';



const communityCards = ['Qs', 'Js', '7d'];

const result = [

  evaluate({ holeCards: ['As', 'Qd'], communityCards }),

  evaluate({ holeCards: ['Ac', 'Tc'], communityCards }),

  evaluate({ holeCards: ['9s', '8s'], communityCards }),

].sort(compare);

```



#### `simulate` (alias: `oddsAsync`)



Given a list of hands and community cards, estimate how often each hand will win or tie using a [Monte Carlo simulation](https://en.wikipedia.org/wiki/Monte_Carlo_method) for roughly estimating the odds of a hand winning or tying.



The `simulate` [generator function](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/GeneratorFunction) returns a [generator](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Generator) that can be used to run as many Monte Carlo simulations as desired, limited by the maximum number of simulations that are possible for a given scenario based upon the provided inputs. (For example, if there are only 2 streets remaining to be dealt with 45 cards remaining in the deck, then there are 45 \* 44 = 1,980 possible simulations.)



```ts

import { Hand, simulate } from '@poker-apprentice/hand-evaluator';



const hand1: Hand = ['As', 'Ks'];

const hand2: Hand = ['Jd', 'Jh'];



const generate = simulate({

  allHoleCards: [hand1, hand2],

  communityCards: ['Qd', 'Js', '8d'],

  expectedCommunityCardCount: 5,

  expectedHoleCardCount: 2,

  minimumHoleCardsUsed: 0,

  maximumHoleCardsUsed: 2,

});



let result = generate.next();

while (!result.done) {

  const hand1WinPercent = ((result[0].wins / result[0].total) * 100).toFixed(1);



  // Output the cumulative results every 500 runs.

  if (result[0].total % 500 === 0) {

    console.log(hand1WinPercent, result);

  }



  result = generate.next();

}



// => "13.8" [{ wins: 69, ties: 0, total: 500 }, { wins: 431, ties: 0, total: 500 }]

// => "13.9" [{ wins: 139, ties: 0, total: 1000 }, { wins: 861, ties: 0, total: 1000 }]

// => "15.4" [{ wins: 231, ties: 0, total: 1500 }, { wins: 1269, ties: 0, total: 1500 }]

// => "14.8" [{ wins: 295, ties: 0, total: 2000 }, { wins: 1705, ties: 0, total: 2000 }]

```



#### `odds`



Given a list of hands and community cards, determine how often each hand will win or tie.



Note: The implementation for this is exhaustive, and it is not practical for scenarios missing more than about 1-2 cards worth of data. It is strongly suggested that the [`simulate`](#simulate) function be used instead.



```ts

import { Hand, odds } from '@poker-apprentice/hand-evaluator';



const hand1: Hand = ['As', 'Ks'];

const hand2: Hand = ['Jd', 'Jh'];



const result = odds([hand1, hand2], {

  communityCards: ['Qd', 'Js', '8d'],

  expectedCommunityCardCount: 5,

  expectedHoleCardCount: 2,

  minimumHoleCardsUsed: 0,

  maximumHoleCardsUsed: 2,

});



console.log(result);

// => [

//      { wins: 304, ties: 0, total: 1980 },

//      { wins: 1676, ties: 0, total: 1980 },

//    ]

```



### Helper Functions



In addition to the core functions, there are some poker game-specific functions that wrap these core functions for ease of use. These functions are effectively the same as calling the `evaluate` of `odds` function directly with the appropriate option values prepopulated.



The functions also perform appropriate error checking/throwing to ensure that the `holeCards` and `communityCards` are of the correct length for each game.



#### `evaluateHoldem`



Evaluates a hand of Texas Hold'em.



```ts

import { evaluateHoldem } from '@poker-apprentice/hand-evaluator';

const hand = evaluateHoldem({

  holeCards: ['As', 'Kd'],

  communityCards: ['9h', '8d', '2c'],

});

```



#### `evaluateOmaha`



Evaluates a hand of Omaha.



```ts

import { evaluateOmaha } from '@poker-apprentice/hand-evaluator';

const hand = evaluateOmaha({

  holeCards: ['Jc', 'Qd', '4h', '7c'],

  communityCards: ['2c', 'Qs', '4c'],

});

```



#### `evaluatePineapple`



Evaluates a hand of Pineapple.



```ts

import { evaluatePineapple } from '@poker-apprentice/hand-evaluator';

const hand = evaluatePineapple({

  holeCards: ['Jc', '7h', 'Qh'],

  communityCards: ['9h', '8d', '2c', '3h', 'Td'],

});

```



#### `evaluateStud`



Evaluates a hand of Stud.



```ts

import { evaluateStud } from '@poker-apprentice/hand-evaluator';

const hand = evaluateStud({ holeCards: ['As', 'Kd', 'Ks', '8s', 'Ac', 'Kh', '4d'] });

```



#### `oddsHoldem`



Calculates the odds of winning or tying a hand of Texas Hold'em.



```ts

import { oddsHoldem } from '@poker-apprentice/hand-evaluator';

const allHoleCards = [

  ['As', 'Kd'],

  ['Ks', '8s'],

];

const communityCards = ['Ts', 'Qs', 'Jd'];

const result = oddsHoldem(allHoleCards, communityCards);

```



#### `oddsOmaha`



Calculates the odds of winning or tying a hand of Omaha.



```ts

import { oddsOmaha } from '@poker-apprentice/hand-evaluator';

const allHoleCards = [

  ['As', 'Kd', 'Td', 'Tc'],

  ['Ks', '8s', '9h', 'Kc'],

];

const communityCards = ['Ts', 'Qs', 'Jd'];

const result = oddsOmaha(allHoleCards, communityCards);

```



#### `oddsPineapple`



Calculates the odds of winning or tying a hand of Pineapple.



```ts

import { oddsPineapple } from '@poker-apprentice/hand-evaluator';

const allHoleCards = [

  ['As', 'Kd', 'Td'],

  ['Ks', '8s', 'Kc'],

];

const communityCards = ['Ts', 'Qs', 'Jd'];

const result = oddsPineapple(allHoleCards, communityCards);

```



#### `oddsStud`



Calculates the odds of winning or tying a hand of Stud.



```ts

import { oddsStud } from '@poker-apprentice/hand-evaluator';

const allHoleCards = [

  ['As', 'Kd', 'Ks', '8s', 'Ac'],

  ['9s', '8s', 'Ts', '6s', '4h'],

];

const result = oddsStud(allHoleCards);

```



#### `simulateHoldem` (alias: `oddsHoldemAsync`)



Estimates the odds of winning or tying a hand of Texas Hold'em.



```ts

import { simulateHoldem } from '@poker-apprentice/hand-evaluator';

const abort = simulateHoldem({

  allHoleCards: [

    ['As', 'Kd'],

    ['Ks', '8s'],

  ],

  communityCards: ['Ts', 'Qs', 'Jd'],

  callback: (result) => console.log(result),

});

```



#### `simulateOmaha` (alias: `oddsOmahaAsync`)



Estimates the odds of winning or tying a hand of Omaha.



```ts

import { simulateOmaha } from '@poker-apprentice/hand-evaluator';

const abort = simulateOmaha({

  allHoleCards: [

    ['As', 'Kd', 'Td', 'Tc'],

    ['Ks', '8s', '9h', 'Kc'],

  ],

  communityCards: ['Ts', 'Qs', 'Jd'],

  callback: (result) => console.log(result),

});

```



#### `simulatePineapple` (alias: `oddsPineappleAsync`)



Estimates the odds of winning or tying a hand of Pineapple.



```ts

import { simulatePineapple } from '@poker-apprentice/hand-evaluator';

const abort = simulatePineapple({

  allHoleCards: [

    ['As', 'Kd', 'Td'],

    ['Ks', '8s', 'Kc'],

  ],

  communityCards: ['Ts', 'Qs', 'Jd'],

  callback: (result) => console.log(result),

});

```



#### `simulateStud` (alias: `oddsStudAsync`)



Estimates the odds of winning or tying a hand of Stud.



```ts

import { simulateStud } from '@poker-apprentice/hand-evaluator';

const abort = simulateStud({

  allHoleCards: [

    ['As', 'Kd', 'Ks', '8s', 'Ac'],

    ['9s', '8s', 'Ts', '6s', '4h'],

  ],

  callback: (result) => console.log(result),

});

```



## Benchmarks



Benchmarked on an Apple M1 MacBook Pro (2020) with 16 GB RAM using macOS Sonoma (14.4.1).



```

┌─────────┬─────────────────────────────────┬───────────┬────────────────────┬──────────┬─────────┐

│ (index) │ Task Name                       │ ops/sec   │ Average Time (ns)  │ Margin   │ Samples │

├─────────┼─────────────────────────────────┼───────────┼────────────────────┼──────────┼─────────┤

│ 0       │ 'evaluate high card'            │ '355,417' │ 2813.5928118446004 │ '±1.07%' │ 177709  │

│ 1       │ 'evaluate one pair'             │ '338,217' │ 2956.6739913315823 │ '±1.22%' │ 169109  │

│ 2       │ 'evaluate two pair'             │ '332,969' │ 3003.276373247081  │ '±1.37%' │ 166485  │

│ 3       │ 'evaluate three of a kind'      │ '356,214' │ 2807.2995373597214 │ '±1.39%' │ 178108  │

│ 4       │ 'evaluate straight'             │ '293,999' │ 3401.3635219867597 │ '±1.27%' │ 147042  │

│ 5       │ 'evaluate flush'                │ '234,729' │ 4260.22771695116   │ '±2.24%' │ 117365  │

│ 6       │ 'evaluate full house'           │ '445,363' │ 2245.3578151797146 │ '±1.44%' │ 222682  │

│ 7       │ 'evaluate four of a kind'       │ '435,199' │ 2297.794512868328  │ '±1.54%' │ 217600  │

│ 8       │ 'evaluate straight flush'       │ '379,529' │ 2634.8410718516025 │ '±1.13%' │ 189765  │

│ 9       │ 'evaluate royal flush'          │ '341,783' │ 2925.830758606707  │ '±1.42%' │ 170892  │

│ 10      │ 'odds holdem heads up to flop'  │ '60'      │ 16660399.096774053 │ '±0.33%' │ 31      │

│ 11      │ 'odds holdem heads up to turn'  │ '2,649'   │ 377453.67849057174 │ '±2.17%' │ 1325    │

│ 12      │ 'odds holdem heads up to river' │ '107,341' │ 9316.064299157219  │ '±1.50%' │ 53671   │

│ 13      │ 'odds holdem multiway to flop'  │ '39'      │ 25622593.799999684 │ '±0.21%' │ 20      │

│ 14      │ 'odds holdem multiway to turn'  │ '1,597'   │ 625997.5319148765  │ '±2.03%' │ 799     │

│ 15      │ 'odds holdem multiway to river' │ '59,267'  │ 16872.57771478776  │ '±1.56%' │ 29634   │

└─────────┴─────────────────────────────────┴───────────┴────────────────────┴──────────┴─────────┘

```



## Development



Contributions are welcome. Please create an issue in the project first to discuss any possible enhancements, bugs, or other changes prior to submitting a pull request. Alternatively, browse existing issues if interested in providing a fix.



### Environment Setup



1. Install [yarn](https://classic.yarnpkg.com/lang/en/docs/install/) and [git](https://git-scm.com/book/en/v2/Getting-Started-Installing-Git).

2. Clone this repository: `git clone [email protected]:poker-apprentice/hand-evaluator.git`

3. Install dependencies: `yarn install`



### Run tests



To run the full test suite:



```

yarn test

```



To run a specific test:



```

yarn test compare.test.ts           # matches test file name

yarn test -t "compare"              # matches test name/description

```



**NOTE:** Profiling is disabled until Node v20 is supported, per [this GitHub issue](https://github.com/hyj1991/v8-profiler-next/issues/65).



To run tests and run profiler:



```

yarn test:profile                   # runs full test suite

yarn test:profile compare.test.ts   # matches test file name

yarn test:profile -t "compare"      # matches test name/description

```



This will create one `.cpuprofile` file per test under the `profiles/` folder. To open these files in Google Chrome:



1. Navigate to [chrome://inspect].

2. Click "Open dedicated DevTools for Node".

3. Select the "Profiler" tab.

4. Click the "Load" button, and select your file.



To remove old `.cpuprofile` files:



```

yarn clean

```



### Run linter



```

yarn lint

```



### Run formatter



```

yarn format

```



### Run benchmarking



```

yarn benchmark

```



### Build package



```

yarn build

```