How to return elements with the highest occurrence in list?

Question

So I was attempting to make a function which will takes a single argument numlist (a non-empty list of numbers), and returns the sorted list of numbers which appear with the highest frequency in numlist.

So far I have managed to create a dictionary (numbers as keys and their frequencies as values). But I still want to find which one of them has the maximum value and return it. Thing is I dont know how to compare them. Now there are certain one-liners like this

max(stats, key=stats.get)

But what if there are multiple values meeting that requirement?

mode([5, 1, 1, 5])
#I'm guessing this should return [1, 5] if sorted...

How would you handle it? Thanks for any help on that!

Here is my code:

def mode(numlist):

    mylist = numlist
    dic = {}

    for num in mylist:
        if num in dic:
            dic[num] += 1
        else:
            dic[num] = 1
     # try to get the max value and return them in a set form like [1, 0]    

Answer 1

You can use a Counter which returns a dict like object where elements are stored as dictionary keys and their counts are stored as dictionary values.

from collections import Counter

def mode(my_list):
    ct = Counter(my_list)
    max_value = max(ct.values())
    return sorted(key for key, value in ct.items() if value == max_value)

Demo:

In [46]: mode([5, 1, 1, 5])
Out[46]: [1, 5]

Answer 2

Sticking to your current implementation, you can sort the values of your dictionary, then just get all the keys of your dictionary that match that maximum value:

So, you can do something like this at the end of your method:

vals = max(dic.values())
return [k for k, v in dic.items() if v == vals]

vals will hold the maximum value to indicate that is the value of the repeating item. Then we create a list comprehension that goes through the dictionary to get all keys that match that value.

Putting it together:

def mode(numlist):

    mylist = numlist
    dic = {}

    for num in mylist:
        if num in dic:
            dic[num] += 1
        else:
            dic[num] = 1

    vals = max(dic.values())
    return [k for k, v in dic.items() if v == vals]


print(mode([5, 1, 1, 5]))

Output:

[1, 5]