Partition a list in Python 3.7

partition.py

from typing import Dict, Tuple, Any, List

def make_tuple_partitions(
    unique_values: List[Any], num_partitions: int
) -> Dict[Tuple[int, int], Tuple[Any, Any]]:
    """
    Given a list of values, return a dictionary with (the_index, the_index + 1) as the keys
    and (chunk_start_value, chunk_end_value) as the values such that the chunks are equal
    or close to equal in size.

    The last key's 1th value should be -1.
    """

    length = len(unique_values)

    if length < num_partitions:
        raise NotEnoughValues
    if length == num_partitions:
        return unique_values

    first, last = unique_values[0], unique_values[-1]
    chunk_size = int(length / num_partitions)

    prev_end = chunk_size
    prev_value = first
    index_of_last_chunk = length - chunk_size - 1

    partitions = []

    for index in range(chunk_size, index_of_last_chunk, chunk_size):
        partitions.append((prev_value, unique_values[index]))
        prev_end = index
        prev_value = unique_values[index]

    partitions.append((prev_value, last))

    partition_dict = {}
    last_idx = len(partitions) - 1
    for idx, value in enumerate(partitions):
        if idx == last_idx:
            key = (idx, -1)
        else:
            key = (idx, idx + 1)
        partition_dict[key] = value

    return partition_dict