issues: 230158616

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id node_id number title user state locked assignee milestone comments created_at updated_at closed_at author_association active_lock_reason draft pull_request body reactions performed_via_github_app state_reason repo type
230158616 MDU6SXNzdWUyMzAxNTg2MTY= 1415 Save arbitrary Python objects to netCDF 2941720 open 0     5 2017-05-20T14:58:42Z 2019-04-21T05:08:03Z   CONTRIBUTOR      

I am looking to transition from pandas to xarray, and the only feature that I am really missing is the ability to seamlessly save arrays of python objects to hdf5 (or netCDF). This might be an issue for the backend netCDF4 libraries instead, but I thought I would post it here first to see what the opinions were about this functionality.

For context, Pandas allows this by using pytables' ObjectAtom to serialize the object using pickle, then saves as a variable length bytes data type. It is already possible to do this using netCDF4, by applying to each object in the array np.fromstring(pickle.dumps(obj), dtype=np.uint8), and saving these using a uint8 VLType. Then retrieving is simply pickle.reads(obj.tostring()) for each array.

I know pickle can be a security problem, it can cause an problem if you try to save a numerical array that accidently has dtype=object (pandas gives a warning), and that this is probably quite slow (I think pandas pickles a list containing all the objects for speed), but it would be incredibly convenient.

 
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