Why doesn't my function to remove duplicates in-place work? [duplicate]

Question

I created a function to take a list as input and remove the duplicates without creating a new array. However, the output is wrong. How can I fix this? and is there a simpler way to do it? I am new to Python

def remove_duplicates(duplicatelist):
    for i in duplicatelist:
        num = 0
        while num < len(duplicatelist)-1:
            #the following line checks to see if there is a 
            #duplicate. It also makes sure that num = i is not being
            #counted as  duplicate because if you have a value of 2 at index 2,
            #then this should not be counted as a duplicate if it's the only one
            if i == duplicatelist[num] and i !=num :
                duplicatelist.remove(duplicatelist[num])
            num = num + 1
    print(duplicatelist)

remove_duplicates([1, 1, 2, 3, 3, 4, 5, 6, 6, 6, 7])
#output is: [1, 3, 4, 6, 7] but this is wrong.

Answer 1

This is different from what you're trying, but if you use the set data structure, it would automatically filter duplicates. Here's one dumb way to do it:

def remove_duplicates(duplicatelist):
    duplicatelist = list(set(duplicatelist))  # first convert to set, then back to a list, reusing the variable name
    print(duplicatelist)

remove_duplicates([1, 1, 2, 3, 3, 4, 5, 6, 6, 6, 7])

Source: https://docs.python.org/3/library/stdtypes.html#set-types-set-frozenset