Sorting lists prioritizing letters before numbers

Sorting lists prioritizing letters before numbers - Printable Version

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Sorting lists prioritizing letters before numbers - Ratherfastmofo - Nov-21-2018

Hi guys,

I'm a very new coder so your help means a lot.

I'm trying to sort a list which unsorted might look like this:

001 123
001 Beta 123
402 123
403 123
402 CxR 123
192 UqS 123
001 Alpha 123
309 223
001 038
007 Bond 123

I want to sort this list so that the first three characters are sorted by number, but after that letters are prioritized in sorting. Thus i want the code to return the list sorted like so:

001 Alpha 123
001 Beta 123
001 038
001 123
007 Bond 123
192 UqS 123
309 223
402 CxR 123
402 123
403 123

How do i sort a list like so?

Thanks, guys.

RE: Sorting lists prioritizing letters before numbers - Gribouillis - Nov-21-2018

Ratherfastmofo Wrote:i want the code to return the list sorted like so

Please post the code to show what it currently returns.

RE: Sorting lists prioritizing letters before numbers - Ratherfastmofo - Nov-21-2018

(Nov-21-2018, 09:43 AM)Gribouillis Wrote:
Ratherfastmofo Wrote:i want the code to return the list sorted like so
Please post the code to show what it currently returns.

Currently I've just used the sorted() function to sort a list in the usual pattern. I just want to hear weather there is a way to customize the sorting priorities in the given pattern.

RE: Sorting lists prioritizing letters before numbers - stranac - Nov-21-2018

You'll need to write a custom key function.
You can learn more in the Sorting HOW TO.

RE: Sorting lists prioritizing letters before numbers - DeaD_EyE - Nov-21-2018

This key function should help.
Maybe it can be optimized.

def key(text):
    offset = ord('z') + 1
    # getting the first 3 chars and convert it to int
    result = [int(text[:3])]
    # iterate over the rest. Whitespace is excluded
    for char in text[4:]:
        if char.isdigit():
            # Add 122 to integer to get a lower prio
            result.append(int(char) + offset)
        else:
            # otherwise just return the ord of char
            result.append(ord(char))
    # result is a list
    return result

The sort function works as follows:

For each element, the key-function is called with this element.
The returned value is a list. A list is sorted by first element, then by second an so on..
The key function just modifies the values for integer, but not for normal letters and other symbols.
I guess it can be optimized. This is just the first shoot.

RE: Sorting lists prioritizing letters before numbers - woooee - Nov-21-2018

Split the list into two lists, one containing the alpha lines and one containing the number lines. Sort each one. Merge the number list to the alpha list.