quick sort in place

quick_sort_inplace.py

def quick_sort_partition(sequence, left, right):
    '''
    In place sorts the subsequence of sequence[left:right]

    '''
    pivot_value = random.choice(sequence[left:right])
    pivot_index = sequence.index(pivot_value)

    sequence[pivot_index], sequence[right]  = sequence[right], sequence[pivot_index]
  
    for index in range(left, right):
        if sequence[index] <= pivot_value:
            sequence[index], sequence[left] = sequence[left], sequence[index]
            left += 1

    sequence[right], sequence[left] = sequence[left], sequence[right]

    return left

def quick_sort_inplace(sequence, left=None, right=None):
    '''
    Quicksort randomly chooses a pivot value to populate a greater than or less than list.
    Recursively calls quick_sort to create smaller and smaller sorted lists, until lists of length 1 or 0 remain.
    '''
    if left < right:
        new_pivot = quick_sort_partition(sequence, left, right)
        quick_sort_inplace(sequence, left, new_pivot-1)
        quick_sort_inplace(sequence, new_pivot+1, right)