def test_pattern_factory():
""" Test hopfield_network.pattern_tools """
import neurodynex.hopfield_network.pattern_tools as tools
pattern_size = 6
factory = tools.PatternFactory(pattern_size)
p1 = factory.create_checkerboard()
assert len(p1) == pattern_size
def test_overlap():
""" Test hopfield_network.pattern_tools overlap"""
import neurodynex.hopfield_network.pattern_tools as tools
pattern_size = 10
factory = tools.PatternFactory(pattern_size)
p1 = factory.create_checkerboard()
p2 = factory.create_all_on()
overlap = tools.compute_overlap(p1, p2)
assert overlap == 0.0 # works for checkerboards with even valued size
def run_hf_demo(pattern_size=4, nr_random_patterns=3, reference_pattern=0,
initially_flipped_pixels=3, nr_iterations=6, random_seed=None):
"""
Simple demo.
Args:
pattern_size:
nr_random_patterns:
reference_pattern:
initially_flipped_pixels:
nr_iterations:
random_seed:
Returns:
"""
# instantiate a hofpfield network
hopfield_net = network.HopfieldNetwork(pattern_size**2)
# for the demo, use a seed to get a reproducible pattern
np.random.seed(random_seed)
# instantiate a pattern factory
factory = pattern_tools.PatternFactory(pattern_size, pattern_size)
# create a checkerboard pattern and add it to the pattern list
checkerboard = factory.create_checkerboard()
pattern_list = [checkerboard]
# add random patterns to the list
pattern_list.extend(factory.create_random_pattern_list(nr_random_patterns, on_probability=0.5))
hfplot.plot_pattern_list(pattern_list)
# let the hopfield network "learn" the patterns. Note: they are not stored
# explicitly but only network weights are updated !
hopfield_net.store_patterns(pattern_list)
# how similar are the random patterns? Check the overlaps
overlap_matrix = pattern_tools.compute_overlap_matrix(pattern_list)
hfplot.plot_overlap_matrix(overlap_matrix)
# create a noisy version of a pattern and use that to initialize the network
noisy_init_state = pattern_tools.flip_n(pattern_list[reference_pattern], initially_flipped_pixels)
hopfield_net.set_state_from_pattern(noisy_init_state)
# uncomment the following line to enable a PROBABILISTIC network dynamic
# hopfield_net.set_dynamics_probabilistic_sync(2.5)
# uncomment the following line to enable an ASYNCHRONOUS network dynamic
# hopfield_net.set_dynamics_sign_async()
# run the network dynamics and record the network state at every time step
states = hopfield_net.run_with_monitoring(nr_iterations)
# each network state is a vector. reshape it to the same shape used to create the patterns.
states_as_patterns = factory.reshape_patterns(states)
# plot the states of the network
hfplot.plot_state_sequence_and_overlap(states_as_patterns, pattern_list, reference_pattern)
plt.show()
def run_user_function_demo():
def upd_random(state_s0, weights):
nr_neurons = len(state_s0)
random_neuron_idx_list = np.random.permutation(int(len(state_s0) / 2))
state_s1 = state_s0.copy()
for i in range(len(random_neuron_idx_list)):
state_s1[i] = -1 if (np.random.rand() < .5) else +1
return state_s1
hopfield_net = network.HopfieldNetwork(6**2)
hopfield_net.set_dynamics_to_user_function(upd_random)
# for the demo, use a seed to get a reproducible pattern
# instantiate a pattern factory
factory = pattern_tools.PatternFactory(6, 6)
# create a checkerboard pattern and add it to the pattern list
checkerboard = factory.create_checkerboard()
pattern_list = [checkerboard]
# add random patterns to the list
pattern_list.extend(
factory.create_random_pattern_list(4, on_probability=0.5))
hfplot.plot_pattern_list(pattern_list)
# let the hopfield network "learn" the patterns. Note: they are not stored
# explicitly but only network weights are updated !
hopfield_net.store_patterns(pattern_list)
hopfield_net.set_state_from_pattern(pattern_list[0])
# uncomment the following line to enable a PROBABILISTIC network dynamic
# hopfield_net.set_dynamics_probabilistic_sync(2.5)
# uncomment the following line to enable an ASYNCHRONOUS network dynamic
# hopfield_net.set_dynamics_sign_async()
# run the network dynamics and record the network state at every time step
states = hopfield_net.run_with_monitoring(5)
# each network state is a vector. reshape it to the same shape used to create the patterns.
states_as_patterns = factory.reshape_patterns(states)
# plot the states of the network
hfplot.plot_state_sequence_and_overlap(states_as_patterns, pattern_list, 0)
plt.show()
#smatplotlib inline
from neurodynex.hopfield_network import network, pattern_tools, plot_tools
pattern_size = 5
# create an instance of the class HopfieldNetwork
hopfield_net = network.HopfieldNetwork(nr_neurons=pattern_size**2)
# instantiate a pattern factory
factory = pattern_tools.PatternFactory(pattern_size, pattern_size)
# create a checkerboard pattern and add it to the pattern list
checkerboard = factory.create_checkerboard()
pattern_list = [checkerboard]
# add random patterns to the list
pattern_list.extend(
factory.create_random_pattern_list(nr_patterns=3, on_probability=0.5))
plot_tools.plot_pattern_list(pattern_list)
# how similar are the random patterns and the checkerboard? Check the overlaps
overlap_matrix = pattern_tools.compute_overlap_matrix(pattern_list)
plot_tools.plot_overlap_matrix(overlap_matrix)
# let the hopfield network "learn" the patterns. Note: they are not stored
# explicitly but only network weights are updated !
hopfield_net.store_patterns(pattern_list)
# create a noisy version of a pattern and use that to initialize the network
noisy_init_state = pattern_tools.flip_n(checkerboard, nr_of_flips=4)
hopfield_net.set_state_from_pattern(noisy_init_state)
# from this initial state, let the network dynamics evolve.
states = hopfield_net.run_with_monitoring(nr_steps=4)
