Question

I’d like to sort into new lists those items in this list…

truc = [['12', 'brett', 5548],
       ['22.3', 'troy', 9514],
       ['8.1', 'hings', 12635],
       ['34.2', 'dab', 17666],
       ['4q3', 'sigma', 18065],
       ['4q3', 'delta', 18068]]

… grouping them using the last field, into bins of size 3500
So, the ideal result would be this:

firstSort = [['34.2', 'dab', 17666],
            ['4q3', 'sigma', 18065],
            ['4q3', 'delta', 18068]]

secondSort = [['22.3', 'troy', 9514],
             ['8.1', 'hings', 12635]]

lastSort = ['12', 'brett', 5548]

I tried to use the itertools.groupby() function, but i am not capable of find a way to specify the bin size.

Answer 1

This is trivial to do without itertools

truc = [['12', 'brett', 5548],
       ['22.3', 'troy', 9514],
       ['8.1', 'hings', 12635],
       ['34.2', 'dab', 17666],
       ['4q3', 'sigma', 18065],
       ['4q3', 'delta', 18068]]

truc.sort(key=lambda a:a[-1])
groups = [[]]
last_row = None
for row in truc:
    if last_row is not None and row[-1] - last_row[-1] > 3500:
        groups.append([])
    last_row = row
    groups[-1].append(row)

import pprint
pprint.pprint(groups)

Output:

[[['12', 'brett', 5548]],
 [['22.3', 'troy', 9514], ['8.1', 'hings', 12635]],
 [['34.2', 'dab', 17666], ['4q3', 'sigma', 18065], ['4q3', 'delta', 18068]]]