al = 'a ą b c ć d e ę f g h i j k l ł m n ń o ó p r s ś t u w y z ź ż'.split()
def decoder(char, key):
	upper = char.isupper()
	try:
		outchar=key[char.lower()]
	except KeyError:
		outchar = char
	if upper:
		outchar = outchar.upper()
	return outchar

def ranks(f):
    frequencies = {}
    for line in f:
        for char in line:
            if not char.lower() in al:
                    continue
            if char.lower() in frequencies:
                frequencies[char.lower()] += 1
            else:
                frequencies[char.lower()] = 1

            
    return sorted([(i[1], i[0]) for i in frequencies.items()], reverse=True)
with open('pantad.TXT', encoding='utf8') as f:
    rankspl = ranks(f)

with open('coded.txt', encoding='utf8') as coded:
    rankscoded = ranks(coded)
keylen = min(len(rankspl), len(rankscoded))

rankscombined = zip(rankspl[:keylen], rankscoded[:keylen] )
key = dict([ (i[1][1], i[0][1], )  for i in rankscombined])

with open('decoded.txt','w', encoding='utf8') as fout:
    with open('coded.txt', encoding='utf8') as coded:
        for line in coded:
            decodedline = []
            for char in line:
                decodedline.append(decoder(char, key))
            fout.write(''.join(decodedline))