CODEWITHSUNDEEP
pythonlistsortingcharacter
Arthur Martens
Arthur Martens

Reputation: 73

How to sort a list of strings with a different order?

I am writing a function in Python which can sort my list. The problem is that I don't want it in the same order that the sorted() method used. I tried using the sorting() method, but when I sort this string, which I it comes out like this:

0123456789abcdefghijklmnopqrstuvwxyzßàáäåæçèéêìíîñòóôöøùúüžα

The order I want it to be in is:

0123456789aàáäåæbcçdeèéêfghiìíîjklmnñoòóôöøpqrsßtuùúüvwxyzžα

Now, I've got a list like this (example):

list = ['x', 'h', 'ê', 'ø', '5', 'ž', 'z', 'α', '3', '1']

And I want so sort it. If I'd use the sorted() method, it would look like this:

['1', '3', '5', 'h', 'x', 'z', 'ê', 'ø', 'ž', 'α']

But I want it to be in the same order as the string I gave before.

Upvotes: 5

Views: 4128

Answers (1)

malbarbo
malbarbo

Reputation: 11177

The idea is to associate to each char the index in the specified order and use the indexes of the string chars to do the order comparison.

Note: only works with Python 3

Sort one char strings

ORDER = "0123456789aàáäåæbcçdeèéêfghiìíîjklmnñoòóôöøpqrsßtuùúüvwxyzžα"
# associate each char with the index in the string
# this makes sort faster for multiple invocations when compared with
# ORDER.index(c)
POS = {c:p for (p, c) in enumerate(ORDER)}

lst = ['x', 'h', 'ê', 'ø', '5', 'ž', 'z', 'α', '3', '1']

lst.sort(key = lambda c: POS[c])
# or, suggested by wim
lst.sort(key = POS.get)

Sort any length strings

class MyStrOrder:
    def __init__(self, inner):
        self.inner = inner

    def __lt__(self, other):
        for i in range(min(len(self.inner), len(other.inner))):
            a = POS.get(self.inner[i])
            b = POS.get(other.inner[i])
            if a != b:
                return a < b
        return len(self.inner) < len(other.inner)

lst = ["abc", "ab", "aá"]
lst.sort()
print(lst)

lst = ["abc", "ab", "aá"]
lst.sort(key = MyStrOrder)
print(lst)

Outputs:

['ab', 'abc', 'aá']
['aá', 'ab', 'abc']

Upvotes: 10

Related Questions