Finding the mode of a list using ONLY loops and creating lists in python

Question

I have been trying to figure out how to find the mode of a list WITHOUT using sorting functions nor importing any modules for quite awhile now... Here's what I have so far:

d = {}
def mode():
    for i in mode:
        if i in d:
            d[i] += 1
        else:
            d[i] = 1
    return

How do I find the output such as the following:

print(mode([1, 5, 6, 1, 1, 2]))
[1]
print(mode([5, 6, 7, 8, 9]))
[5, 6, 7, 8, 9]

Thanks a bunch!

mode argument is missing and name it values or sth else ... mode(values) — rebeling, Sep 28 '15 at 22:41
d[i] = d.get(i, 0) + 1 as a replacement for the if else block — rebeling, Sep 28 '15 at 22:42

score 0 · Answer 1 · answered Sep 28 '15 at 22:59

You need to count the occurrences in your dict and extract the max based on the value returning the list itself if there is no mode.

def mode(l):
     d= {}
    for i in l:
        d.setdefault(i, 0)
        d[i] += 1
    mx = max(d,key=d.get)
    return d[mx] if d[mx] > 1 else l

score -1 · Answer 2 · answered Sep 28 '15 at 22:44

-1

Use a dictionary with the value as the key and a count as value. If you're using Python 3, this is the Counter data type.

When you've tallied all the entries, find the max of the values. Make a list comprehension of all elements with that value.

answered Sep 28 '15 at 22:44

Prune

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OP said no imports, so `collections.Counter` is out. Relatedly, `Counter` was added in 2.7, so you don't need Python 3 to have access to it. – ShadowRanger Sep 28 '15 at 23:13

Finding the mode of a list using ONLY loops and creating lists in python

2 Answers2