On Thu, Sep 06, 2007 at 09:16:55AM -0500, Ross Bates wrote:
> A Saturday 01 September 2007, Ross Bates escrigué:
> >> Hi All - I'm new to Python and I am learning the language by
> >> experimenting with PyTables, so this question might seem simple.
> >>
> >> I want to be able to execute a table.where condition with a list of
> >> values for the column. Like a SQL 'in' statement
> >>
> >> So instead of this repeating the column
> >>
> >> table.where("(src_id == 'x') | ((src_id) == 'y')")
> >>
> >> it would be something like this:
> >>
> >> table.where("(src_id == 'x' | 'y' ")
> >>
> >> I've tried a variety of things and just want to make sure there is
> >> not something I'm missing.
>
> >Currently, you should keep using the former expression. The later
> >expression is actually a shortcut of the first one, but this is not
> >supported by PyTables (actually, by the integrated numexpr package),
> >and it is not in our plans to implement it anytime soon.
>
>
> Hi Francesc - thanks for the response and nice welcome. I'm really
> digging Python so far,
>
> I understand that the condensed where statement is not supported by
> the numexpr package, the question I have which remains is more about
> Python best practices in this situation.
>
> If I had a program which accepted 1 or more users parameters as values
> for the table.where clause, is dynamically building the condition to
> acheive an in-kernel select acceptable?
>
> If it's possible, I like to avoid code that generates code so I'm just
> wondering if that's the only option.
I'm sorry, but I don't completely understand what you mean. In
principle yes, the option I mentioned you is the only option, but, could
you please give an explicit example on what you are trying to do?
Knowing this perhaps I can come with more insightful suggestions.
Cheers,
Francesc
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