Not strictly necessary if your list is small, but I’d probably approach this in a “stream-processing” fashion: define a generator that takes your input iterable, and yields the elements grouped into runs of numbers differing by <= 15. Then you can use that to generate your dictionary easily.
def grouper(iterable):
prev = None
group = []
for item in iterable:
if prev is None or item - prev <= 15:
group.append(item)
else:
yield group
group = [item]
prev = item
if group:
yield group
numbers = [123, 124, 128, 160, 167, 213, 215, 230, 245, 255, 257, 400, 401, 402, 430]
dict(enumerate(grouper(numbers), 1))
prints:
{1: [123, 124, 128],
2: [160, 167],
3: [213, 215, 230, 245, 255, 257],
4: [400, 401, 402],
5: [430]}
As a bonus, this lets you even group your runs for potentially-infinite lists (as long as they’re sorted, of course). You could also stick the index generation part into the generator itself (instead of using enumerate
) as a minor enhancement.