Crude implementation in QuickSort

quick_sort.py

def swap(target, i, j):
    temp = target[i]
    target[i] = target[j]
    target[j] = temp

def quick_sort(target, low_index, high_index):
    orig_low_index = low_index
    orig_high_index = high_index
    sub_array_size = high_index - low_index
    pivot_index = low_index + sub_array_size / 2
    pivot_val = target[pivot_index]

    if low_index >= high_index:
        return

    while low_index <= high_index:

        # Look for an out of place element on the left
        while target[low_index] < pivot_val:
            low_index += 1

        # Look for an out of place element on the right
        while target[high_index] > pivot_val:
            high_index -= 1

        swap(target, low_index, high_index)
        low_index += 1
        high_index -= 1

    quick_sort(target, orig_low_index, high_index)
    quick_sort(target, low_index, orig_high_index)