AttributeError: type object 'h5py.h5r.Reference' has no attribute '__reduce_cython__' on using "from keras.utils import HDF5Matrix"
I got the solution. It was because I was importing both HDF5Matrix and tables in same program. Due to some reason both cannot be imported in  same program. I think it is because both make use of h5py in backend, so importing both is causing some conflict.
I just reinstalled python into my system with all necessary modules. But when I run a program with the import statement from keras.utils import HDF5Matrix, it is giving attribute error. The place where the error is coming is: File "h5py\h5r.pxd", line 21, in init h5py._conv
  File "h5py\h5r.pyx", line 145, in init h5py.h5r. But when I run the same statement in the IDLE directly, it is not giving any error. So, what is the cause of error. I have not posted my code because most of it is irrelevant as the Interpreter is not going past the import statement. Also, before I reinstalled Python, the code was working fine. So, what can be the problem.