[Yt-dev] Column Density derived field

[Matthew Turk]

Hi Stephen,

For what it's worth, I also agree with Cameron that calling it
"ColumnDensity" is a bit too broad, and maybe it should be called
something like "RadialColumnDensity" or something similarly indicative
of its nature to indicate it's not the same as a projection.

Can you also maybe take a minute to outline a couple use cases?

-Matt

On Tue, Oct 25, 2011 at 9:23 AM, Stephen Skory <s at skory.us> wrote:
> Cameron & Matt,
>
> What it's called isn't a big concern to me, but I see what you're
> saying, Cameron.
>
>> The issue about field detector is an interesting one.  I guess I don't
>> understand why asking for 'x' is a problem.  Your solution sounds good
>> to me.
>
> When I wasn't looking for the field detector as I am now, what was
> happening is data['x' or 'y' or 'z'] would return some values that
> weren't cell centers, which when passed to the interpolation stuff
> would not work. So asking for 'x' wasn't a problem, but the values it
> returned were not what I wanted.
>
>> How fast is the code?  It looks to me like it probably does quite a
>> few expensive operations
>
> Running on a 40^3 dataset on my 2.0Ghz i7 lappy on battery power gives
> about 300,000 cells/second for the whole process (HEALPix with 5
> surfaces + interpolation). I think I'm close to making it parallel,
> but some weird stuff is popping up that I don't quite understand just
> yet.
>
>>... would you be willing at some point in the
>> future to explore replacing it with an actual adaptive healpix
>> operation?
>
> Perhaps. It seems to me before you said that that would be quite a bit
> more difficult, which looking at the source is true. Everything in
> this current attempt is using numpy vectorization, so I don't know how
> much more speed can be squeezed out of this method.
>
> --
> Stephen Skory
> s at skory.us
> http://stephenskory.com/
> 510.621.3687 (google voice)
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