Stupid simple Theano example that allows using all previous states in a `scan`

scan_all_states.py

in_seq = T.matrix(name='input')

initial_state = theano.shared(np.array([0., 0.]), name='initial')
initial_scan_state = T.zeros((in_seq.shape[0], initial_state.shape[0]))
initial_scan_state = T.set_subtensor(initial_scan_state[0], initial_state)

def fun(i, current_element, state):
        res = T.sum(state[:i], axis=0)+current_element
        return T.set_subtensor(state[i], res)


r, u = theano.scan(fun, sequences=[T.arange(in_seq.shape[0]), in_seq], outputs_info=[initial_scan_state])


scf = theano.function(inputs=[in_seq], outputs=r[-1])