A Friday 26 June 2009 17:44:48 Didier Roissé escrigué:
> Hello,
> I created a HDF5 file containing an array with the following dimension
> (5000,1). I notice a big difference file size between the array creation
> with createCArray and createEArray.
> For creation of the table with createCArray, i use this script :
>
> h5ft=openFile('test_carray.h5','w')
> ca=h5ft.createCArray(h5ft.root,"foo",Float32Col(),(5000,1),"carray test")
> for ii in range(5000):
> ca[ii][0]=1.0
Here is culprit. When assigning to a PyTables object, always specify the
indexes in one shot. For example, replace the above line by:
ca[ii,0]=1.0
and you are done. Or you can avoid the last index completely too:
ca[ii]=1.0
as the input is broadcasted to the affected index.
What was happening here is that ca[ii] returns the element ii of the CArray as
a (temporary) NumPy array, and when you do ca[ii][0]=1.0, you are modifying
that NumPy array, not the value on disk.
Hope that helps,
--
Francesc Alted
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