CODEWITHSUNDEEP
pythonarrayssorting
BaronBeef
BaronBeef

Reputation: 15

Python Arrays Minimize Values

I am trying to change the values of an array into smaller numbers like

list = [1,3,7,3] into list = [1,2,3,2]

I already have a few lines of code to keep it organized.

def sortItems(list):
    counts = collections.Counter(list)
    sortedlist = sorted(list, key=counts.get, reverse=True)
    return sortedlist

been crawling all over W3Schools and other forums but still unsure

Upvotes: 0

Views: 115

Answers (2)

Raymond Kwok
Raymond Kwok

Reputation: 2541

l = [1, 3, 7, 3] 

unique_keys = set(l)

mappings = {key: val for val, key in enumerate(sorted(unique_keys), 1)}

print(list(map(mappings.get, l)))

Orders are preserved by the sorted().

Upvotes: 3

Mateen Ulhaq
Mateen Ulhaq

Reputation: 27201

(This answer addresses the information in the comments.)

For a performant implementation, count, sort keys, then repeat and flatmap.

from collections import Counter
from itertools import repeat

def flatmap_repeat_sort_count(xs):
    counts = Counter(xs)
    keys = sorted(counts.keys())
    return [
        x
        for i, k in enumerate(keys, start=1)
        for x in repeat(i, counts[k])
    ]

Example runs:

>>> flatmap_repeat_sort_count([1, 3, 7, 3])
[1, 2, 2, 3]

>>> flatmap_repeat_sort_count([7, 1, 3, 1])
[1, 1, 2, 3]

Upvotes: 0

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