Python recursive function is not using argument correctly

Question

Just can not wrap my head why this code would not work:

def list_flatten(a_list):
    for item in a_list:
        if isinstance(item, list):
            list_flatten(item)
        else:
            yield item

print(list(list_flatten([["A"]])))

print(list(list_flatten(["A", ["B"], "C"])))

Expecting:

["A"] and
["A", "B", "C"]

Getting

[] and
["A", "C"]

Side note: Do not want to use chain.from_iterable, because it will breakdown the strings too, like ["123"] might end up ["1","2","3"]

Does this answer your question? [Why does my recursive function return None?](https://stackoverflow.com/questions/17778372/why-does-my-recursive-function-return-none) — MisterMiyagi, Mar 07 '22 at 20:31
`list_flatten(item)` creates a new iterator (a generator), nothin is done with it and it is discarded — juanpa.arrivillaga, Mar 07 '22 at 20:32

score 3 · Accepted Answer · answered Mar 07 '22 at 20:26

3

You're not doing anything with the result of your recursive call.

Change

list_flatten(item)

to

yield from list_flatten(item)

and you should be good to go. (See the docs for yield from.)

answered Mar 07 '22 at 20:26

AKX

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Python recursive function is not using argument correctly

1 Answers1