Python - finding complement of 2 lists

I'm looking for a method that would allow me to check what elements are missing when comparing 2 lists. A lot like in this thread but I want to write this in NumPy Python.

Complement of Two Lists?

import numpy as np

numbers = np.array([1,2,3,4,5,6,7,8,9])
A = np.array([2,5,6,9])

def listComplementElements(list1, list2):

    storeResults = []

    for i in list1:
        for j in list2:

            if i != j:
                #write to storeResults if 2 numbers are different
                storeResults.append(i)
            else:
                #if numebrs are equal break out of the loop
                break

    return storeResults            

result = listComplementElements(numbers, A)
print(result) #expected result [1,3,4,7,8]

At the moment the output looks like this: [1, 1, 1, 1, 3, 3, 3, 3, 4, 4, 4, 4, 5, 6, 6, 7, 7, 7, 7, 8, 8, 8, 8, 9, 9, 9]

What am I doing wrong?

This is what you were going for:

import numpy as np

numbers = np.array([1, 2, 3, 4, 5, 6, 7, 8, 9])
A = np.array([2, 5, 6, 9])

def listComplementElements(list1, list2):
    storeResults = []

    for num in list1:
        if num not in list2: # this will essentially iterate your list behind the scenes
            storeResults.append(num)

    return storeResults

result = listComplementElements(numbers, A)
print(result) #expected result [1,3,4,7,8]

Prints:

[1, 3, 4, 7, 8]

You should only have one loop and then say if not in to evaluate the relationship with the second list. Otherwise you will loop unnecessarily and like you saw, it will output the result many times! Furthermore, using operators like is in or not in makes your code more readable than trying to comprehend many nested loops :)