On Wed, Jul 8, 2020 at 7:13 PM Inada Naoki <songofacandy@gmail.com> wrote:
I think this comparison is unfair.

well, benchmarks always lie ....
> d.items()[0]    vs    list(d.items())[0]

Should be compared with `next(iter(d.items())`

why? the entire point of this idea is to have indexing syntax -- we can already use the iteration protocol top do this. Not that it's a bad idea to time that too, but since under the hood it's doing the same or less work, I'm not sure what the point is.

> d.keys()[-1]     vs      list(d.keys())[-1]

Should be compared with `next(reversed(d.keys()))`, or `next(reversed(d))`.

Same point - the idea is to have indexing syntax. Though yes, it would be good to see how it compares. But I know predicting performance is usually wrong, but this is going to require a full traversal of the underlying keys in either case.
> random.choice(d.items())   vs    random.choice(list(d.items()))

Should be compared with `random.choice(items_list)` with `items_list =
list(d.items())` setup too.

I don't follow this one -- could you explain? what is items_list ?

But what this didn't check is how bad the performance could be for what I expect would be a bad performance case -- indexing teh keys repeatedly:

for i in lots_of_indexes:


keys_list = list(a_dict.keys)
for it in lots_of_indexes:

I suspect it wouldn't take all that many indexes for making a list a better option.

But again, we are badk to use cases. As Stephen pointed out no one has produced an actualy production code use case.

I myself have wanted this (the random.choice option) -- but it wasn't production code it was a learning exercise, specifically:


I can imagine there would be that use case in real world code, but I haven't had it.



Inada Naoki  <songofacandy@gmail.com>
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