PH Evaluator Python package (phevaluator)

Description

PH Evaluator is designed for evaluating poker hands with more than 5 cards. Instead of traversing all the combinations, it uses a perfect hash algorithm to get the hand strength from a pre-computed hash table, which only costs very few CPU cycles and considerably small memory (~100kb for the 7 card evaluation). With slight modification, the same algorithm can be also applied to evaluating Omaha poker hands.

The full API documentation is published at https://henryrlee.github.io/PokerHandEvaluator/python.

Installation

The library requires Python 3.10 or newer.

The evaluator is implemented as a C extension (phevaluator._pheval) that wraps the C sources in the repository's cpp directory, so a C compiler and pip 21.3 or newer are required to build from source. Older pip versions build out-of-tree and cannot reach the cpp directory.

• from release on PyPI

  pip install phevaluator
  

• from source code

  Build from within the repository (the sibling cpp directory is used to compile the extension):

  pip install .
  

  If you are using pip older than 21.3, either upgrade pip:

  pip install --upgrade pip
  

  or pass the --use-feature=in-tree-build flag so the build can access the cpp sources:

  pip install --use-feature=in-tree-build .
  

Using the library

The main function is the evaluate_cards function.

from phevaluator.evaluator import evaluate_cards

p1 = evaluate_cards("9c", "4c", "4s", "9d", "4h", "Qc", "6c")
p2 = evaluate_cards("9c", "4c", "4s", "9d", "4h", "2c", "9h")

# The rank is an integer from 1 (strongest) to 7462 (weakest), so a smaller
# value means a stronger hand. Player 2 has a stronger hand here.
print(f"The rank of the hand in player 1 is {p1}") # 292
print(f"The rank of the hand in player 2 is {p2}") # 236

The returned value is the rank of the hand among all 7462 distinct five-card hands. It is identical to the return value of Cactus Kev's evaluator: 1 is the best possible hand (a Royal Straight Flush) and 7462 is the worst. A smaller value is always a stronger hand, so you can compare two hands directly (e.g. p2 < p1 means player 2 wins).

The function can take both numbers and card strings (with a format like: 'Ah' or '2C'). Usage examples can be seen in examples.py.

Omaha and Pot Limit Omaha

Omaha-style hands (five community cards followed by the hole cards) can be evaluated with the dedicated functions:

from phevaluator import evaluate_omaha_cards  # 4 hole cards
from phevaluator import evaluate_plo4_cards   # 4 hole cards (alias of Omaha)
from phevaluator import evaluate_plo5_cards   # 5 hole cards
from phevaluator import evaluate_plo6_cards   # 6 hole cards

# 5 community cards + 4 hole cards. The return value is a rank in the same
# 1 (strongest) to 7462 (weakest) scale as evaluate_cards, computed from the
# best five-card hand allowed by the Omaha rules.
evaluate_omaha_cards("4c", "5c", "6c", "7s", "8s", "2c", "9c", "As", "Kd")

evaluate_plo5_cards and evaluate_plo6_cards require the package to be built with PLO5/PLO6 support. Their lookup tables are very large (hundreds of MB of generated C source each), so they are opt-in: set the PHEVALUATOR_BUILD_PLO environment variable when installing from the repository.

# Build with PLO5 and PLO6 support (also accepts "5", "6", or "all")
PHEVALUATOR_BUILD_PLO=5,6 pip install .

Calling evaluate_plo5_cards/evaluate_plo6_cards on a package built without the corresponding support raises NotImplementedError. evaluate_plo4_cards (and evaluate_omaha_cards) are always available.

Card Id

We can use an integer to represent a card. The two least significant bits represent the 4 suits, ranging from 0-3. The rest of it represents the 13 ranks, ranging from 0-12.

More specifically, the ranks are:

deuce = 0, trey = 1, four = 2, five = 3, six = 4, seven = 5, eight = 6, nine = 7, ten = 8, jack = 9, queen = 10, king = 11, ace = 12.

And the suits are: club = 0, diamond = 1, heart = 2, spade = 3

So that you can use rank * 4 + suit to get the card ID.

Technically, it is fine to swap the suit values, as long as the suits are uniquely mapped to the values 0, 1, 2, and 3. If you do swap the suit values, make sure to update the mapping in the source code as well (suit_map in card.py).

The complete card Id mapping can be found below. The rows are the ranks from 2 to Ace, and the columns are the suits: club, diamond, heart and spade.

Test

• The functionality of the evaluators is tested against CSV test data in the test_data/ folder (generated by the C++ evaluator), covering five-card, six-card, seven-card, and PLO4 (Omaha) evaluations.
• The Card module is tested against the Card Id table documented above.

The tests import the compiled phevaluator._pheval extension, so build it first (for example with an editable install, pip install -e .) and run the tests from the repository root of the Python package:

python -m unittest discover -v

Contributing

Thank you for your interest in contributing to the Python package of PHEvaluator! To ensure a smooth contribution process, please follow the guidelines below.

Requirements

• Python 3.10 or newer
• A C compiler (the evaluator is built as a C extension)
• Ruff for linting and formatting
• mypy for type checking

Code style

• Follow the Black code style.
• Write type hints following PEP 484.
• Include docstrings following PEP 257.
• Lint and format code using Ruff.

Development Setup

Install development dependencies:

pip install '.[dev]'

Checking Changes

You can install the package from the source code in editable mode:

pip install -e .

This allows the installed package to automatically reflect changes made in the phevaluator folder.

Building the Package

To build the package, run the following command:

python -m build

This will create a dist folder containing the built package.

Install the built package for testing:

pip install dist/*.whl

Check whether your distribution's long description will render correctly on PyPI:

python -m twine check dist/*