Union and intersection of two arrays
Advice 1

PEP 8 has some (minor) complains: the names of functions and their arguments should be funky_functions instead of funkyFunctions, and funky_argument instead of funkyArgument.

Advice 2

In Python, you can say

def funky1():
    for i in range(10):
        yield i

def funky2():
    arr = []
    for i in range(10):
        arr.append(i)
    return arr


So you may come up with:

def intersection(array_one, array_two):
    array_one_index = 0
    array_two_index = 0
    size_of_array_one = len(array_one)
    size_of_array_two = len(array_two)
    while array_one_index &lt; size_of_array_one and array_two_index &lt; size_of_array_two:
        if array_one[array_one_index] &lt; array_two[array_two_index]:
            array_one_index += 1
        elif array_one[array_one_index] &gt; array_two[array_two_index]:
            array_two_index += 1
        else:
            yield array_one[array_one_index]
            array_one_index += 1
            array_two_index += 1


Advice 3

Your union does not omit duplicates. You can deal with them in a following manner:

def union(array_one, array_two):
    array_one_index = 0
    array_two_index = 0
    size_of_array_one = len(array_one)
    size_of_array_two = len(array_two)
    while array_one_index &lt; size_of_array_one and array_two_index &lt; size_of_array_two:
        if array_one_index &gt; 0 and array_one[array_one_index - 1] == array_one[array_one_index]:
            array_one_index += 1
            continue
        if array_two_index &gt; 0 and array_two[array_two_index - 1] == array_two[array_two_index]:
            array_two_index += 1
            continue
        if array_one[array_one_index] &lt; array_two[array_two_index]:
            yield array_one[array_one_index]
            array_one_index += 1
        elif array_one[array_one_index] &gt; array_two[array_two_index]:
            yield array_two[array_two_index]
            array_two_index += 1
        else:
            yield array_one[array_one_index]
            array_one_index += 1
            array_two_index += 1

    while array_two_index &lt; size_of_array_two:
        if array_two_index &gt; 0 and array_two[array_two_index - 1] == array_two[array_two_index]:
            array_two_index += 1
            continue
        yield array_two[array_two_index]
        array_two_index += 1

    while array_one_index &lt; size_of_array_one:
        if array_one_index &gt; 0 and array_one[array_one_index - 1] == array_one[array_one_index]:
            array_one_index += 1
            continue
        yield array_one[array_one_index]
        array_one_index += 1


Advice 4

Note also that you don't need

if arrayOneIndex == sizeOfArrayOne:


in union; only one of the "leftover" loop will iterate at least once.

Hope that helps.