These two seem both array to me.
# suppose that test_data has [1000,728] shape
print (test_data[0:1,:].shape)
# output [1,728]
print (test_data[0,:].shape)
# output [728,]
I tried these two arrays in keras sequential model.predict_classes(x)
function.
The test_data[0:1,:] works but test_data[0,:] gives error.