Is there a better way to create a list of None objects?

[Stephen Tucker]

Thanks for this feedback, Chris, Matthieu. Both are spot on - and thanks
for the timing comparison, Matthieu. I suppose I didn't think to try the
solution you suggest because I didn't think that I would end up with a
single list, but 8 of them.

OK, I'll stop wriggling.

Stephen.

On Thu, Aug 12, 2021 at 10:22 AM Matthieu Dartiailh <m.dartiailh at gmail.com>
wrote:

> You can achieve the same result by writing:
> [None] * 8
>
> Comparing both cases in IPython I get:
>
> In [1]: %timeit list((None,)*8)
> 110 ns ± 0.785 ns per loop (mean ± std. dev. of 7 runs, 10000000 loops
> each)
>
> In [2]: %timeit [None] * 8
> 88.2 ns ± 0.432 ns per loop (mean ± std. dev. of 7 runs, 10000000 loops
> each)
>
> So the list multiplication appears a bit faster.
>
> Best
>
> Matthieu
>
> Le 8/12/2021 à 10:57 AM, Stephen Tucker a écrit :
> > Hi,
> >
> > I thought I'd share the following piece of code that I have recently
> written
> > (a) to check that what I have done is reasonable - even optimum,
> > (b) to inform others who might be wanting to do similar things, and
> > (c) to invite comment from the community.
> >
> > -------------------------------------------
> >
> > #
> >
> > # Yes: Create an empty list of Band Limits for this language
> >
> > #
> >
> > # Note. The rather complicated logic on the right-hand side of the
> >
> > #       assignment below is used here because none of the following
> >
> > #       alternatives had the desired effect:
> >
> > #
> >
> > # Logic             Effect
> >
> > #
> >
> > # [None * 8]        TypeError: unsupported operand type(s) for *: ...
> >
> > # [(None) * 8]      TypeError: unsupported operand type(s) for *: ...
> >
> > # [((None)) * 8]    TypeError: unsupported operand type(s) for *: ...
> >
> > # [(None,) * 8]     [(None, None, None, None, None, None, None, None)]
> >
> > # list ((None) * 8) TypeError: unsupported operand type(s) for *: ...
> >
> > #
> >
> > diclll_BLim [thisISO_] = list ((None,) * 8)
> >
> >
> > -------------------------------------------
> >
> > Thanks in anticipation.
> >
> > Stephen Tucker.
>
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