Array order in pytables

Question

With pytables's CArray, is there a way to specify the order in which the data is stored on disk (Fortran/C)?

I am looking for something similar to ndarray's order parameter.

Answer 1

You can use the chunkshape parameter that in effect specifies the data order:

http://pytables.github.com/usersguide/libref.html#tables.File.createCArray

For instance, for 2-D data, chunkshape=(2000, 1) would be efficient if data is accessed in Fortran order, and chunkshape=(1, 2000) if it is accessed in C order. You may need to play with the numbers a bit: http://pytables.github.com/usersguide/optimization.html