armstrong.py

# python3.5

import itertools

def isIn(group, elem):
    elem=''.join(sorted(set(elem[0]))),''.join(sorted(set(elem[1])))
    for s in group:
        if s[0]==elem[0]:
            for g in elem[1]:
                if g not in s[1]:
                    return False
            return True
    return False

def add(group, elem):
    elem = ''.join(sorted(set(elem[0]))), ''.join(sorted(elem[1]))
    for symbol in elem[1]:
        found = False
        for s in group:
            if s[0]==elem[0]:
                found = True
                if symbol not in s[1]:
                    group.remove(s)
                    group.add((elem[0], ''.join(sorted(symbol+s[1]))))
                break
        if not found:
            group.add((elem[0],symbol))

def getlength(group):
    l = 0
    for elem in group:
        l+=len(elem[1])
    return l

def prettyprint(group, alphabet, numcolumns = 3):
    d = dict(group)
    x = -1
    for key, value in d.items():
        print ("{:>12}".format("".join(key)+"⟶"+"".join(value)), end="")
        x+=1
        if (x == numcolumns):
            x=-1
            print()
    

def armstrong(group, symbols):
    for set1, set2 in itertools.product(itertools.product(symbols, repeat=3),
                                        itertools.product(symbols, repeat=3)):
        set1 = set(set1)
        set2 = set(set2)
        if (set2.issubset(set1)):
            add(group, (set1, set2))
    lastlength = 0
    while lastlength != getlength(group):
        lastlength = getlength(group)
        for symbol1, symbol2, symbol3 in itertools.product(
                itertools.product(symbols, repeat=3), repeat=3):
            symbol1, symbol2, symbol3 = set(symbol1), set(symbol2), set(symbol3)
            if isIn(group, (symbol1,symbol2)):
                add(group, (symbol1.union(symbol3), symbol2.union(symbol3)))
            if isIn(group, (symbol1, symbol2)) and isIn(group, (symbol2, symbol3)):
                add(group, (symbol1, symbol3))
alphabet = 'abcd'
objs = set()
add(objs, ("a", "b"))
add(objs, ("b", "c"))
armstrong(objs, alphabet)
prettyprint(objs, alphabet, 4)