How can I find same values in a list and group together a new list?

Question

From this list:

N = [1,2,2,3,3,3,4,4,4,4,5,5,5,5,5]

I\'m trying to create:

L = [[1],[2,2],[3,3,3],[4,4,4,4],[5,5,5,5,5]]
         


        

Answer 1

Another slightly different solution that doesn't rely on itertools:

#!/usr/bin/env python

def group(items):
    """
    groups a sorted list of integers into sublists based on the integer key
    """
    if len(items) == 0:
        return []

    grouped_items = []
    prev_item, rest_items = items[0], items[1:]

    subgroup = [prev_item]
    for item in rest_items:
        if item != prev_item:
            grouped_items.append(subgroup)
            subgroup = []
        subgroup.append(item)
        prev_item = item

    grouped_items.append(subgroup)
    return grouped_items

print group([1,2,2,3,3,3,4,4,4,4,5,5,5,5,5])
# [[1], [2, 2], [3, 3, 3], [4, 4, 4, 4], [5, 5, 5, 5, 5]]