Dictionary comprehension that contains an (embedded) list comprehension

Question

How do I return each country as the key and a list of cities in that country as the value? Using dictionary and embedded list comprehension? Without using collections

country_city_tuples= [('Netherlands', 'Alkmaar'),
                  ('Netherlands', 'Tilburg'),
                  ('Netherlands', 'Den Bosch'),
                  ('Netherlands', 'Eindhoven'),
                  ('Spain', 'Madrid'),
                  ('Spain', 'Barcelona'),
                  ('Spain', 'Cordoba'),
                  ('Spain', 'Toledo'),
                  ('Italy', 'Milano'),
                  ('Italy', 'Roma')]

post your attempts.. we are not here to do your homework. – Avinash Raj May 23 '19 at 12:14 — Avinash Raj, May 23 '19 at 12:14

score 1 · Accepted Answer · answered May 23 '19 at 12:25

You can do something like this:

my_dict = {item[0]: [subitem for subkey, subitem in country_city_tuples if subkey == item[0]] for item in country_city_tuples}

The output will be like:

{'Netherlands': ['Alkmaar', 'Tilburg', 'Den Bosch', 'Eindhoven'], 'Italy': ['Milano', 'Roma'], 'Spain': ['Madrid', 'Barcelona', 'Cordoba', 'Toledo']}

Dictionary comprehension that contains an (embedded) list comprehension

1 Answers1