Sorted dict with str+int keys in python

May 27, 2024

I was trying to sort a dict, where i had values such as:
‘e0’, ‘e3’, ‘e9’, …
but sadly python sorts it by "first letters", and when i have an ‘e12’ value it puts it before ‘e3’
can someone pls help me write a function which will sort it well
example dict for sorting:

{'e0': 50, 'e12': 89, 'e3': 110, 'e90': 18, 'e8': 82, 'e11': 40}

expected result:

{'e0': 50, 'e3': 110, 'e8': 82, 'e11': 40, 'e12': 89, 'e90': 18}

I’ve tried to do it sorted(); of course, it didn’t work, but I also tried

sorted(thedict.items(), key=lambda x: int(x[0]))

but it doesn’t work correctly too (described in the beginning)

>Solution :

I’d save the keys as tuple ('e', 12), before creating the dict().
If that’s not an option, then you have to break it apart and get the number and sort it based on that:

def _sort_dict(d):
    def _by_num(key):
        return int(key[1:])

    return dict(sorted(d.items(), key=lambda x: _by_num(x[0])))

print(_sort_dict({'e0': 50, 'e12': 89, 'e3': 110, 'e90': 18, 'e8': 82, 'e11': 40}))

Prints

{‘e0’: 50, ‘e3’: 110, ‘e8’: 82, ‘e11’: 40, ‘e12’: 89, ‘e90’: 18}

Note

If the alpha part was longer, we can get the ending digits:


import re

def _sort_dict(d):
    def _by_num(key):
        num = re.search(r'\d*$', key)[0]
        return int(num) if num else -1

    return dict(sorted(d.items(), key=lambda x: _by_num(x[0])))


print(_sort_dict({'eeee0': 50, 'eeee12': 89, 'eeee3': 110, 'ee90': 18, 'eaaa8': 82, 'ebbb11': 40, 'eeee': 50}))

Prints

{‘eeee’: 50, ‘eeee0’: 50, ‘eeee3’: 110, ‘eaaa8’: 82, ‘ebbb11’: 40,
‘eeee12’: 89, ‘ee90’: 18}

Note:

If you may have had, only alphas, or only numeric or both, you can use this pattern, r'(^[^0-9]*)(\d*)$', generate a tuple of (alpha, numeric) and then sort it:

Code

import re


def _sort_dict(d):
    def _by_num(key):
        p = r'(^[^0-9]*)(\d*)$'
        alpha, num = re.findall(p, key)[0]
        return (alpha, int(num if num else -1))

    return dict(sorted(d.items(), key=lambda x: _by_num(x[0])))


print(_sort_dict({'eeee0': 50, 'eeee12': 89, 'eeee3': 110,
      'ee90': 18, 'eaaa8': 82, 'ebbb11': 40, 'eeee': 50, '0': 50}))