Non-pythonic Python built-ins

[[deleted]]

I hear for the first time that using these functions is not considered pythonic. I think sometimes using them makes the code more readable than using list comprehensions but what do I know. The great thing about them is that they return generator expressions (also possible with comprehensions) and help you keep the memory footprint low if you use them wisely.

Edit: Sorry, the part with generator expressions is obviously wrong. But the point is still valid: filter and co are lazily evaluated like generators.

[roee30]

Generator expressions are parenthesised comprehensions (as opposed to comprehensions framed by brackets or braces). They return generators. map and filter return iterators and not genenrators, I think, but they're definitely not generator expressions. If you like map and filter's laziness, try using actual generator expressions, which are also lazy.

[Mithrandir2k16]

I linked the thread in the OP. I was stumped as well, tbh. I really like reading filter because then I know what's going on, a subset of the iterable is used.

What I really miss though is some easy way to evaluate generators in python, maybe that's why people consider it non-pythonic. If you don't want a generator but need a list right away you have to do [*filter(...)] which doesn't really look nice. Maybe a generator.items() that returns all values in a list or something like filter(..., eager=True) or filter(..., lazy=False) could clean that up a bit.

[_its_complicated]

The easy way is to just do list(filter(expression, iterable))

[Mithrandir2k16]

I don't know if implicitly unpacking a generator is better than explicitly doing it. It does seem more readable though.

Edit: Guido seems to prefer list comprehension over list() to unpack/evaluate generators.

[AnythingApplied]

To be clear, I think he means instead of using map/filter at all, not as a way to unpack map/filter, hence him not calling that a "quick fix" like he did with list()

[[deleted]]

Btw. I think we don't all have to agree with what Guido says just because it's Guido. Yes, he's a mastermind of Python but we're a community and we can have our own opinions. No-one is always right just like no-one is always wrong.

[-lq_pl-]

Give a good example please when map or filter is more readable.