Re: [Pytables-users] Combining in-kernel queries with out-of-core computations

[Anthony S. <sc...@gm...>]

Hello Jon,

I believe that the where() method just uses the Expr / numexpr
functionality under the covers.  Anything that you can do in Expr you
should be able to do in where().  Can you provide a short example where
this is not the case?

Be Well
Anthony

On Tue, Jun 5, 2012 at 6:17 PM, Jon Wilson <js...@fn...> wrote:

> Hi all,
> In looking through the docs, I see two very nice features: the .where()
> query method, and the tables.Expr computation mechanism.  But, it
> doesn't appear to be possible to combine the two.  It appears that, if I
> want to compute some function of my columns, but only for certain rows,
> I have two options.
>  - I can use tables.Expr to compute the function, and then filter the
> results in python
>  - I can use mytable.where() to select the rows I'm interested in, and
> then compute the function in python
>
> Am I missing anything?  Is it possible to perform fast out-of-core
> computations with numexpr, but only on a subset of the existing rows?
> Regards,
> Jon Wilson
>
>
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