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Jaroslav Hajek wrote:
>> sumskipnan counts also the number of non-NaNs.
>> [s,c]=sumskipnan(...)
>>
>> computing both s and c in a single step is beneficial for estimating
>> mean, variance and other statistics.
>>
>
> well, you can do
>
> nans = isnan (x);
> x(nans) = 0;
> s = sum (x, dim);
> c = size (x, dim) - sum (nans);
>
> Not exactly as fast as doing it all in a single loop, but simplistic.
I guess, you meant
c = size (x, dim) - sum (nans,dim);
In terms of simplicity,
[s,c]=sumskipnan(x,dim);
will win.
>
>>> Besides, I think the fact that the NaN package shadows Octave's
>>> built-in functions is very dangerous and confusing, even though I
>>> understand the motivation. I think this package should not be
>>> installed by default.
>>
>> Where do you see a danger ? Please explain.
>>
>
> It seems that sometimes users (especially windows users) get this
> package unknowingly loaded. Not that this is your fault, just that it
> probably shouldn't be on by default in distributions.
>
> The more painful issue is that it makes the package less attractive to
> use - for instance, if I want to use the nanmean function to get
> nan-free mean, but I *don't* want the built-in mean to be shadowed
> (because the replacement is slower).
Therefore, it would be nice to have a pre-compiled sumskipnan that
limits the performance hit. And their is certainly room for further
improvement.
>
> OTOH, I admit sometimes it may be good to be able to just substitute
> the default stats by nan-free ones.
>
> I think it would be better to split the package in two, say, "nan" and
> "nan-shadow" that would separate the two uses, because right now I
> need to manually edit "path" after the package is loaded if I don't
> want the default funcs to be shadowed.
I donot know how this should work. We have already two competing
stats-packages, the default one and the NaN-toolbox. A third option
would just increase the confusion. Personally, I'd prefer merging the
advantages of both approaches in a single solution.
However, I do not see any *danger* is using the NaN-toolbox.
>
> cheers
>
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