Poker Hand Evaluator

In pure python

27 January 2011, Alvin Liang

Introduction

This is a pure python library to calculate the rank of the best poker hand out of 5, 6, or 7 cards. It does not run the board for you, or calculate winning percentage, EV, or anything like that. But if you give it two hands and the same board, you will be able to tell which hand wins.

It is nowhere near as fast as pypoker-eval, but it works if you can't use C for some reason (the early stages of the first MIT pokerbot competition come to mind). The core algorithm is slower, and you obviously don't have the speed of C.

Quick Start

from pokereval.card import Card
from pokereval.hand_evaluator import HandEvaluator

hole = [Card(2, 1), Card(2, 2)]
board = []
score = HandEvaluator.evaluate_hand(hole, board)

Rank is 2-14 representing 2-A, while suit is 1-4 representing spades, hearts, diamonds, clubs.

The Card constructor accepts two arguments, rank, and suit.

aceOfSpades = Card(14, 1)
twoOfDiamonds = Card(2, 3)

Algorithm

The algorithm for 5 cards is just a port of the algorithm that used to be at the following URL. (I purposely broke the link because it now hosts a malware site.) httx://wwx.suffecool.net/poker/evaluator.html

I came up with the 6 and 7 card evaluators myself, using a very similar card representation and applying some of the same ideas with prime numbers. The idea was to strike a balance between lookup table size and speed.

Also, I haven't included the code I used to generate the lookup tables, but you should be able to do that with a simpler, slower algorithm. Maybe I'll add that later as well.

There is also a two-card ranking/percentile algorithm that is unrelated to the rest and may get cleaned up later. We used it at one point for some pre-flop evaluation. Credit to Zach Wissner-Gross for developing this.

Documentation is sparse at the moment, sorry about that, and obviously I did not really bother to package it or clean it up. I may or may not work on this in the future. Basically, I made it, so why not release it?

Contributors

• Me! Go me!
• Zach Wissner-Gross (2-card algorithm)
• arslr (Fixes for other Python versions)
• Jim Kelly (Help with packaging, additional documentation)