Sort and Print Nested String in Python

Question

So here's my code. I separated the items in the list and printed them:

mylist = [["Orange", "Banana"], ["Grape", "Orange", "Apple"]]

for s in mylist:
print '\n'.join(s)

Orange
Banana
Apple
Grape
Orange

But I want the list alphabetized. I've tried this, but it only sorts the items within their nests:

for s in mylist:
print '\n'.join(sorted(s))

Banana
Orange
Apple
Grape
Orange

How do you print and sort items in a nested list all together?

Possible duplicate of [Flatten, remove duplicates, and sort a list of lists in python](https://stackoverflow.com/questions/36582889/flatten-remove-duplicates-and-sort-a-list-of-lists-in-python) — Sumner Evans, Jul 31 '17 at 17:05
@SumnerEvans not that one, no duplicate removal needed. cannot find a suitable one, but that's a very simple question indeed. — Jean-François Fabre, Jul 31 '17 at 18:01

Jean-François Fabre · Answer 1 · 2017-07-31T18:06:32.497

1

Basically it's combining flattening and sorting. Flattening is handled in various ways here: Making a flat list out of list of lists in Python. Sorting is built-in.

My version:

chain using itertools.chain then sort:

import itertools

for i in sorted(itertools.chain.from_iterable(mylist)):
    print(i)

Or without itertools, generate a list comprehension (which has the benefit of passing a list to sorted so sorted doesn't need to force iteration):

for i in sorted([x for sl in mylist for x in sl]):
    print(i)

(the most efficient way would probably be sorted(list(itertools.chain.from_iterable(mylist))), though)

edited Jul 31 '17 at 18:06

answered Jul 31 '17 at 17:04

Jean-François Fabre

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No need for the inner list comprehension on the second option. `sorted` can accept a generator expression: `sorted(x for sl in mylist for x in sl)` – Sumner Evans Jul 31 '17 at 17:08
no need but it is faster because else `sorted` has to iterate to build a list anyway and iteration is slow. – Jean-François Fabre Jul 31 '17 at 17:57

Sort and Print Nested String in Python

1 Answers1