let's try this

from numpy import argmax

# define input string
data = 'ABCZ'
print(data)

# define universe of possible input values
alphabet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'

# define a mapping of chars to integers
char_to_int = dict((c, i) for i, c in enumerate(alphabet))
int_to_char = dict((i, c) for i, c in enumerate(alphabet))

# integer encode input data
integer_encoded = [char_to_int[char] for char in data]
print(integer_encoded)

# one hot encode
onehot_encoded = list()

for value in integer_encoded:
	letter = [0 for _ in range(len(alphabet))]
	letter[value] = 1
	onehot_encoded.append(letter)

print(onehot_encoded)


# invert encoding
inverted = int_to_char[argmax(onehot_encoded[1])]
print(inverted)