How can I make def function that have same effect with Counter class?

Question

I want to make def function which have same effect with Counter class and It's most_common function. And I success to make def function to find only the mode of a string like this way.

def most_common_char_count(s):
    dict = {}
    for n in s:
        keys = dict.keys()
        if n in keys:
            dict[n] += 1
        else:
            dict[n] = 1
    return dict

str1 = 'dajklvkdafjkd;ajfeqipjjfdas;fjkdsal;'
most_commons = most_common_char_count(str1) 
print(most_common_char_count(str1))

But I want to add most_command function to this def function. This is a program like that can print up to the Nth order of frequency. So I made an algorithm for the program, but I don't know how to implement it. The algorithm is as follows.

def most_common_char_count(s, n=None): #it have two parameters
    dictionary = {} #and I made string in dictionary
    for n in s:
        if n == None: #If n==none, returns the entire dictionary as a list of tuples
            dictionary[n] += 1
            return(list(zip(dict.keys(),dict.values())))
        else: #Returns the n most frequent items as a list of tuples.
            
s = 'dajklvkdafjkd;ajfeqipjjfdas;fjkdsal;'
most_commons = most_common_char_count(s, 4) 
print(4, most_commons)
print(most_common_char_count(s))

So if I put print(4, most_commons) , output will be

[('j', 6), ('d', 5), ('a', 5), ('k', 4)]

I don't know what code to write in the else statement. And if there are any additional errors, please let me know.

Answer 1

After you create the dictionary, sort it by the counts and return the first n elements.

from collections import defaultdict

def most_common_char_count(s, n=None):
    counts = defaultdict(lambda: 0)
    for item in s:
        counts[item] += 1

    if n is None:
        return counts
    else:
        return dict(sorted(counts.entries(), key=lambda k, v: v, reverse=True)[:n])

Some other points:

1. Don't use dict as a variable name, it's the name of a built-in type and function. I changed it to counts .
2. You can't use n as both the function parameter and the iteration variable in for .
3. You can use defaultdict instead of explicitly testing if the key is in the dictionary.