How do I convert letters to their corresponding number value?

Question

I am relatively new to python. As a mini-project, I am creating a program that involves taking one-word two strings and converting each character to their corresponding letter value (e.g A = 1, C = 3, Z = 26). I want to find a way to do this without assigning all 26 letters to a number in a dictionary. Every algorithm I have found online doesn't seem to be working or I don't understand it.

I am completely lost on how to go about this. I would appreciate it if someone could point me in the right direction.

Thanks

See [chr](https://docs.python.org/3/library/functions.html#chr) and [ord](https://docs.python.org/3/library/functions.html#ord) — Thierry Lathuille, May 20 '20 at 17:25

score 0 · Answer 1 · edited Jun 20 '20 at 09:12

You can use ascii code. For example:

num = ord(letter1.lower()) - ord('a') + 1

each character is represented by a number in ascii code. You can convert your letter to ascii code using ord, and subtract from it the ascii code of letter 'a'. All alphabet is sequential in ascii table. I added .lower() since you should split it by two cases, if you have upper case or lower case. Full code will look something like this (given a letter in variable letter1:

if letter`.islower():
   num = ord(letter1) - ord('a') + 1
else:
   num = ord(letter1) - ord('A') + 1

(the +1 is if your start counting from 1 rather then 0)

score 0 · Answer 2 · answered May 20 '20 at 17:26

0

You can use the built in ord function to return the unicode code point (as an integer) for any character.

>>> ord('A')
65

You can subtract an offset from that if you like.

>>> offset = ord('A') - 1
>>> ord('A') - offset
1
>>> ord('B') - offset
2

answered May 20 '20 at 17:26

timgeb

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score 0 · Answer 3 · edited Jun 20 '20 at 09:12

0

Here:

string = 'hello'
nums = ''

for l in string:
    nums += str(ord(l)-96)+' '

print(nums)

The ord() function returns an integer representing the Unicode character. For example, 'a' in Unicode character is 96, 'b' is 97 and 'c' is 98.

edited Jun 20 '20 at 09:12

Community

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answered May 20 '20 at 17:26

Red

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this answer would be improved with a brief description of what `ord` does. – Woodrow Barlow May 20 '20 at 20:42

score 0 · Answer 4 · answered May 20 '20 at 17:27

0

Use ord:

A='lksdfj'
for c in A:
    print(c,':',ord(c))

Output:

l : 108
k : 107
s : 115
d : 100
f : 102
j : 106

answered May 20 '20 at 17:27

Code Pope

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score 0 · Answer 5 · answered May 20 '20 at 17:27

The built-in string module provides strings containing the alphabet. You can use a one-liner to make a dict from letter to number:

import string
letter_to_number = {l:n+1 for (l,n) in zip(string.ascii_uppercase, range(len(string.ascii_uppercase)))}
# {'A': 1, 'B': 2, 'C': 3, 'D': 4, 'E': 5, 'F': 6, 'G': 7, 'H': 8, 'I': 9, 'J': 10, 'K': 11, 'L': 12, 'M': 13, 'N': 14, 'O': 15, 'P': 16, 'Q': 17, 'R': 18, 'S': 19, 'T': 20, 'U': 21, 'V': 22, 'W': 23, 'X': 24, 'Y': 25, 'Z': 26}

score 0 · Accepted Answer · answered May 20 '20 at 17:29

0

for example...

letter = 'c'
print(ord(letter)-96)

answered May 20 '20 at 17:29

jv95

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How do I convert letters to their corresponding number value?

6 Answers6

Here: