How to convert alphabet to numbers?-CodePudding

Trying to convert alphabet to numbers. An example of what I'm trying to do is convert the word "green" to a list of corresponding number index values: [6, 17, 4, 4, 13]

My eventual goal is to use it in a password encrypter thing, where I can convert the letters to numbers, do some math on the numbers so they're still on [0, 25], and then convert those numbers back to letters, so it's mixed up.

Here's code of what I've done so far:

def lettertonumber(word):
    flength = len(word)
    fcodera = "abcdefghijklmnopqrstuvwxyz"
    fcoderb = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25]
    fcoderlength = len(fcodera)
    numkey = []

    i = 0
    g = 0
    while i < flength:  # flength is the length of 'word' (in the case of 'green', 5)
        while g < fcoderlength:  # fcoderlength is the length of the alphabet (26)
            if word[i] == fcodera[g]:  # to convert it to the number
                numkey.append(fcoderb[g])  # fcoderb is a list with [0, 1, 2, 3... 24, 25] for the alphabet
            g = g   1
        i = i   1

    return numkey

word = 'green'
numberkey = lettertonumber(word)

The output of print(numberkey) is [6]. My question, then, is considering the loops that I have, why am I only getting one iteration of the i loop worth of numbers in numberkey[], when I should be getting as many as the length of the word (so that print(numberkey) outputs [6, 17, 4, 4, 13])

Sorry if my question is phrased poorly or unhelpful, this is my first question! Also sorry for my ignorance with Python -- I just learned it yesterday! Thank you!

CodePudding user response：

You can use the ord function to get the ascii value in decimal, then subtract 97. This can all be done within a list comprehension.

>>> word = 'green'
>>> [ord(l.lower()) - 97 for l in word]
[6, 17, 4, 4, 13]

If you wanted to go backwards, you can take the list of numbers and use the chr function to convert back to letters. Then join together with a blank string.

>>> numbers = [6, 17, 4, 4, 13]
>>> ''.join([chr(n   97) for n in numbers])
'green'

CodePudding user response：

I made changes to your code. Here it is:

def letterToNumber(word):
    numKey = []

    tmp = 0
    for i in word:
        tmp = i.lower()
        numKey.append(ord(tmp.lower()) - ord('a'))

    return numKey

word = 'green'
numberKey = letterToNumber(word)
print(numberKey)

Just renamed variable names to be more clear, and instead of finding index in alphabet string, i just used built-in ord() function which can convert character to ASCII code value. When I get ASCII code value for character I can convert it to index in alphabet by subtracting ord(character) and ord('a').

CodePudding user response：

Well I haven't really answered your question fully but here is a simple that function that converts numbers into letters.

def convert_to_alphabet(number_list):
    alphabet = "abcdefghijklmnopqrstuvwxyz"
    alphabet_list = []
    for i in number_list:
        alphabet_list.append(alphabet[i])
    return alphabet_list

CodePudding user response：

i think this is what you searching for:

def lettertonumber(word):
    alphabet = []
    for i in range(97, 123):
        e = chr(i)
        alphabet.append(e)

    list_of_indexes = []
    for i in word:
        e = alphabet.index(i)
        list_of_indexes.append(e)

    print(list_of_indexes)


lettertonumber("green")