On Sun, Dec 29, 2019 at 8:14 PM Andrew Barnert <abarn...@yahoo.com> wrote:
> On Dec 29, 2019, at 16:08, David Mertz <me...@gnosis.cx> wrote:
> >
> > * There is absolutely no need to lose any efficiency by making the
> statistics functions more friendly. All we need is an optional parameter
> whose spelling I've suggested as `on_nan` (but bikeshed freely). Under at
> least one value of that parameter, we can keep EXACTLY the current
> implementation, with all its warts and virtues as-is. Maybe a spelling for
> that option could be 'unsafe' or 'fast'?
>
> This seems like the right way to go to me.
> However, rather than coming up with appropriately-general implementations
> of each of these things, wouldn’t taking a key function to pass through to
> sorted be simpler for some?
No, it wouldn't. That cannot deal with the 'raise' or 'poison' behaviors.
Moreover, coming up with statistics.is_nan() and statistics.total_order()
really isn't hard. Chris Barker already provided a pretty good is_nan()
that we could use.
In particular, coming up with a total_order function that works for all
> valid number-like types is difficult; letting the user pass
> key=math.total_order or decimal.Decimal.compare_total or
> partial(decimal.Decimal.compare_total, context=my_context) or whatever is
> appropriate is a lot simpler and a lot more flexible. Anyone who knows
> that’s what they want should know how to pass it.
>
Here it is. I could save a line by not using the 'else'.
def total_order(x):
if is_nan(x):
return (math.copysign(1, x))
else:
return (0, x)
Plus, finding the median_low or _high, with a key function actually seems
> useful even without NaNs. “Find the median employee by salary” doesn’t seem
> like a meaningless operation.
>
I'll give you that. That could be useful. However, I feel like that's too
much for the module itself. It's easy to write it yourself with no
function.
median_employee = statistics.median((e.salary, e) for e in employees)[1]
That's not so terribly much work for the user of the module.
--
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from the bellies of the hungry; books from the hands of the
uneducated; technology from the underdeveloped; and putting
advocates of freedom in prisons. Intellectual property is
to the 21st century what the slave trade was to the 16th.
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