Saving numpy array in mongodb

Question

I have a couple of MongoDB documents wherein one my the fields is best represented as a matrix (numpy array). I would like to save this document to MongoDB, how do I do this?

{ 'name' : 'subject1', 'image_name' : 'blah/foo.png', 'feature1' : np.array(...) } 

Answer 1

For a 1D numpy array, you can use lists:

# serialize 1D array x record['feature1'] = x.tolist()  # deserialize 1D array x x = np.fromiter( record['feature1'] ) 

For multidimensional data, I believe you'll need to use pickle and pymongo.binary.Binary:

# serialize 2D array y record['feature2'] = pymongo.binary.Binary( pickle.dumps( y, protocol=2) ) )  # deserialize 2D array y y = pickle.loads( record['feature2'] )