3D Array of Doubles imported from HDF5

I am able to read 321x321x641 array of doubles stored in an HDF5 file using a programmable source.

h5py.File(‘/Users/…/pixel_0_phi.hdf5’, ‘r’)
a_group_key = list(f.keys())[0]
data = f[a_group_key][()]

Each element in the array is the electrical potential at regular grid location in a 3D cube.
I am having a bear of a time simply displaying the data or slices from the cube. If anyone can point me to a good simple example, that would be great. The data that I am using should look like this: