List comprehension as a statement by itself

Question

I know it can be done in a for loop, but using list comprehension as below looks a little odd to me because it is just a statement without any assignment or being used as part of something else.

Couple of questions: Is there a better way to do this by making the list comprehension part of the set command above, and regardless of a better way to merge set/list comprehension is it 'standard' Python practise to have lines like this?

some_list = [[1,2,3],[4,5,6],[1,2,3]]
myset = set()

[myset.add(tuple(t)) for t in some_list]

print(myset)

List comprehensions for side effects are specifically discouraged. Just write the `for` loop. Or e.g. `set(map(tuple, some_list))`. — jonrsharpe, Aug 23 '22 at 09:52
You need a set comprehension instead of a list comprehension. — quamrana, Aug 23 '22 at 09:54
Does this answer your question? [Python Set Comprehension](https://stackoverflow.com/questions/21770885/python-set-comprehension) — wovano, Aug 23 '22 at 10:34

score 3 · Accepted Answer · answered Aug 23 '22 at 09:53

3

Juste write

myset = {tuple(t) for t in some_list}

answered Aug 23 '22 at 09:53

Holt

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Crikey! I've been dumb all along. I thought {} was just dictionary comprehension, I presumed there was no such thing as set comprehension. I guess this is what happens when you reuse the same brackets :) – Neil Aug 23 '22 at 09:55
1

@Neil The alternative would be `set(tuple(t) for t in some_list)`, or `set(map(tuple, some_list))`… – deceze Aug 23 '22 at 09:58
1

@Neil It's called a *generator expression* and can be used anywhere an *iterable* is expected. – deceze Aug 23 '22 at 10:02

List comprehension as a statement by itself

1 Answers1