python string must contain 1 digit and 1 letter

Question

I made a funtion that requires input of 2 values in a string. I'm trying to make it so that the input must consist of a combination of 1 digit and 1 letter. Example: 3f 5h I have the following code but i can't seem to get the condition of digit and alpha to work. Is it because .isdigit and .isalpha are about all characters?

def chess(value1, value2):

    if len(value1) == 2 and len(value2) == 2:
        for char in value1, value2:
            if char.isalpha() and char.isdigit():
                print("Input is right format.")
            else:
                print("Input is NOT right format.")
    else:
        print("Input is NOT right format.")

value1, value2 = input('values: ') .split()

chess(value1, value2) 

Using only

if char.isalpha():

or

if char.isdigit():

seems to work. But together they don't.

Answer 1

I am assuming you have no clue about regex with my answer but you could do something like this and write a function to check if each space is valid.

def validSpaceFormat(space):
    if len(space) == 2:
        if space[0].isalpha() and space[1].isdigit():
            return True
    return False 

def chess(value1, value2):
    if validSpaceFormat(value1) and validSpaceFormat(value2):
       print("Input correct.")
    else:
        print("Input wrong.")

value1, value2 = input('values: ').split()
chess(value1, value2) 

This is assuming that people will always input moves as "X1 Y2"

isalpha() and isdigit() only work on characters so you need to index each character in the string to check what it is.

Answer 2

Simple way to check if input is of length 2.

if len(a) == 2:
    if (a[0].isdigit() and a[1].isalpha()) or ((a[1].isdigit() and a[0].isalpha())):
        print('yes')
    else:
        print('no')

Answer 3

Answer from BrightOne worked like a charm:

You probably can use regular expressions for this. For now, you can do value1[0].isalpha() and value1[1].isdigit(), and so on.

Answer 4

import re
def chess(value1, value2):
    regex = "^\d[a-h]$"
    return all([re.match(regex, s) for s in (value1, value2)])

\d[a-h] will only match one digit followed by one character in "abcfefgh". the ^ and $ ensure that it only matches strings of length 2. re.match(regex, s) returns None if the string s does not match the regex