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Hi Kim,
I am not sure if it is of any help, but you are aware of the fact that
you can simply give a recarray to the createTable method (as the
'description' parameter), and it will use the dtype from the array?
Also, if the array has data, it will be inserted into the table
on-the-fly.
All the best, Gabriel
On Tue, 2009-07-28 at 16:58 +0200, Kim Hansen wrote:
> Hi pytable users,
>
> Perhaps everyone is on vacation or my questions are too stupid...??
> Anyway here comes another question from a PyTables newbie
>
> I have recently realized that numpy.memmap recarray does not give me
> large enough files on my Win32 OS for me to handle my several GB data
> files, so I have turned to PyTables.
>
> So one of the tasks I am facing is getting Descriptor classes (or
> equivalent dictionaries) to use for table.createTable.
>
> What I have is a bunch of loong numpy.dtype declarations defining the
> numpy recarrays I am using. (They are not nested, they just have many
> fields)
>
> One path is to implement a series of IsDescription classes as
> equivalents of the dtypes I've defined. That is a very boring and
> seems redundant. It is also bad for maintenance as when I adjust or
> add new recarray dtypes i have to remember to also update the
> Description classes. I was therefore hoping that there was either a
> constructor or a factory method available for Description, such that
> you could get an equivalent Description class from, e.g.,
> Description.from_dtype(), just as there is for Atom:
> Atom.from_dtype().
>
> However, that does not seem to be the case?
>
> I've noted I can do the reverse from a table instance:
> table.description._v_dtype
>
> Am I overlooking something?
>
> If not I will get on with implementing it myself (it would be fun
> actually, much funnier than manually defining all them classesI just
> don't want to redo it, if it has already been done).
>
> Cheers,
> Kim
>
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