A Monday 12 May 2008, Nick Bower escrigué:
> > 2. Has anyone contended with managing schema differences between
> > sources? In other words, if I have say 500 loggers, each logging
> > slightly different schemas (ie 100 different columns and so
> > different table definitions), the suggested Pytables way of binding
> > static data definitions for each logger could be unmaintainable.
> > From memory I can dynamically bind class attributes in Python - is
> > this ok?
>
> Ok I found the docs on defining tables with dictionaries instead of
> classes. Fyi this does not work with PyTables:
>
>
> class LoggerRecord(tables.IsDescription):
> pass
>
> LoggerRecord.col1 = tables.Float32Col() # dynamically bind
>
> h5file = tables.openFile("test.h5", mode = "w", title = "test")
> group = h5file.createGroup('/', 'test', 'Test Data')
> table = h5file.createTable(group, 'data', LoggerRecord, 'Data')
>
> Traceback (most recent call last):
> File "<stdin>", line 1, in <module>
> File "/usr/lib/python2.5/site-packages/tables/file.py", line 736,
> in createTable
> chunkshape=chunkshape, byteorder=byteorder)
> File "/usr/lib/python2.5/site-packages/tables/table.py", line 517,
> in __init__
> self.description = Description(descr.columns)
> File "/usr/lib/python2.5/site-packages/tables/description.py", line
> 480, in __init__
> self._g_setPathNames()
> File "/usr/lib/python2.5/site-packages/tables/description.py", line
> 547, in _g_setPathNames
> head = cols[0]
> IndexError: list index out of range
Yes. Using dictionaris is the official way to dinamically define fields
on tables. Assigning fields dynamically to a IsDescription subclass is
not currently supported.
Cheers,
--
Francesc Alted
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