import string

alphamap = dict((c,m + 1) for m,c in enumerate(string.lowercase))
nummap   = dict((m + 1,c) for m,c in enumerate(string.lowercase))

def encnum(texto):
        # Make it lowercase
        texto = texto.lower()
        # Iterate through a-z
        for l in alphamap.keys():
                # replace a-z with 1-26
                texto = texto.replace(l, " " + str(alphamap[l]))
        return texto

print encnum("abcdef")

# Output is  1 2 3 4 5 6