reaction hasher | Python Fiddle

import re

COMPOUND_REGEX = re.compile('[a-zA-Z0-9]+')
REACTION_DIRECTION_REGEX = re.compile('[<=>]+')

class KeggReaction(object):
    def __init__(self, equation):
        self.equation = equation
        
		
    @property
    def is_bidirectional(self):
        return self.__reaction_direction == '<=>'
    
    @property
    def __reaction_direction(self):
        return REACTION_DIRECTION_REGEX.findall(self.equation)[0]
    
    @property
    def __is_reversed(self):
        return self.__reaction_direction == '<='

@property
    def reactants(self):
        return self.__equation_parts[0]
        
    @property
    def products(self):
        return self.__equation_parts[1]
    
    @property
    def __equation_parts(self):
    	reac, prod = self.equation.split('=')
        reac, prod = frozenset(COMPOUND_REGEX.findall(reac)), frozenset(COMPOUND_REGEX.findall(prod))
        if self.is_bidirectional:
            return tuple(sorted((reac, prod), key=hash))
        if self.__is_reversed:
            return prod, reac
        return reac, prod
    
    def __eq__(self, other):
        return other and hash(self) == hash(other)

def __hash__(self):
        return hash((
            frozenset(self.reactants),
            self.is_bidirectional,
            frozenset(self.products)
        ))
	
    def __repr__(self):
        return self.equation

if 1:
    reactions = [
        KeggReaction("C00022 + C00068 => C05125"),
        KeggReaction("C00068 + C00022 => C05125"),
        KeggReaction("C05125 <= C00022 + C00068"),
        KeggReaction("C00022 => C05125 + C00022"),
        KeggReaction("C05125 <=> C00022 + C00068"),
        KeggReaction("C00068 + C00022 <=> C05125"),
    ]
    
    for i, reac1 in enumerate(reactions[:-1]):
        for j, reac2 in enumerate(reactions[i+1:]):
            print reac1
            print reac2
            print 'equals:', reac1 == reac2
            print

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