def reconstruct_images(alg, images, columns, connect_threshold,
desired_activity_mult, min_overlap, img_shape,
out_dir=None):
cols_shape = columns.shape
# Initialize boost matrix.
boost = np.ones(shape=cols_shape[:2])
part_rbuffer = partial(RingBuffer,
input_array=np.zeros(1, dtype=np.bool), copy=True)
# Initialize activity dictionary.
activity = defaultdict(part_rbuffer)
if alg == 'bsp':
# Initialize overlap_sum dictionary.
overlap_sum = defaultdict(part_rbuffer)
distances = calculate_distances(cols_shape)
# Calculate the inhibition_area parameter.
inhibition_area = update_inhibition_area(columns, connect_threshold)
# Calculate the desired activity in a inhibition zone.
desired_activity = desired_activity_mult * inhibition_area
reconstructions = np.zeros_like(images)
# Initialize the activations matrix. This will be used to calculate the
# population and lifetime kurtoses.
activations = np.zeros(shape=(images.shape[0], cols_shape[0],
cols_shape[1]), dtype=np.int)
for i, image, _ in read_input(images):
if alg == 'bsp':
overlap, _ = bsp_overlap(image, columns, min_overlap,
connect_threshold, boost, overlap_sum)
elif alg == 'asp':
# calculate the overlap of the columns with the image.
# (this is a simple count of the number of its connected synapses
# that are receiving active input (p. 3)), ...
overlap = asp_overlap(image, columns, min_overlap,
connect_threshold, boost)
# force sparsity by inhibiting columns, ...
active, _ = inhibit_columns(columns, distances, inhibition_area,
overlap, activity, desired_activity)
# set reconstructions[i][y, x] to (sic, p. 7):
# "[...] the linear superposition of the
# connected synapses of the columns that become active
# when the input is present [...]"
# first, generate a copy of the columns array, where all the synapses
# of all inactive columns are set to 0, ...
active_cols = np.where(active, columns,
np.zeros(shape=(cols_shape[2], cols_shape[3])))
# and then set reconstructions[i] to the linear superposition of the
# synapses of the active columns.
reconstructions[i] = np.nansum(active_cols, axis=(0, 1))
# Store the post-inhibition overlap activity of each column as the
# sum of the overlap of the active columns.
activations[i] = np.nansum(columns, axis=(2, 3))
if out_dir is not None:
if not os.path.exists(out_dir):
os.mkdir(out_dir)
# Rebuild the 256x 256 images from the 16x16 patches.
reconstructions = rebuild_imgs_from_patches(reconstructions, img_shape)
# Scale the pixel values to the range [0, 1].
reconstructions = reconstructions - reconstructions.min()
reconstructions /= reconstructions.max() - reconstructions.min()
# Scale the pixel values to the range [0, 255].
reconstructions *= 255
for i, reconstruct_img in enumerate(reconstructions):
with open(os.path.join(out_dir, 'rec_img_%d.png' % i), 'wb') as fp:
plt.imsave(fname=fp, arr=reconstruct_img, cmap='gray', )
return activations
def spatial_pooler(images, shape, p_connect=0.15, connect_threshold=0.2,
p_inc=0.02, p_dec=0.02, b_inc=0.005, p_mult=0.01,
min_activity_threshold=0.01, desired_activity_mult=0.05,
b_max=4, max_iterations=10000, cycles_to_save=100,
output_file=None):
"""
Implements the main BSP loop (p. 3). It goes continually through the images
set until convergence.
:param images: set of images to learn from. It is an array of shape
(l, m, n) where (l, m) == (shape[0], shape[1]) and
(l, m) == (shape[2], shape[3])
:param shape: the shape of the output array. It must have 4 components, and
(shape[0], shape[1]) == (shape[2], shape[3]).
:param p_connect: probability of the columns mapped to [i, j] to have a
potential synapse to coordinates [k, l], for all i in
shape[0], j in shape[1], k in shape[2], and l in
shape[3].
:param connect_threshold: threshold over which a potential synapse is
considered *connected*. All potential synapses
start with a permanence value within 0.1 of
this parameter.
:param p_inc: the BSP'perm pInc parameter (p. 4). A float that indicates
the amount by which a synapse'perm permanence must be
incremented.
:param p_dec: the BSP'perm pDec parameter (p. 4). A float that indicates
the amount by which a synapse'perm permanence must be
decremented.
:param b_inc: the BSP'perm bInc parameter (p. 4). A float that indicates
the amount by which a column'perm boost must be incremented.
:param p_mult: the BSP'perm pMult parameter (p. 4). A float that indicates
the amount by which a synapse'perm permanence must be
multiplied.
:param min_activity_threshold: the BSP's minActivityThreshold parameter
(p. 4).
:param desired_activity_mult: the BSP's desiredActivityMult parameter
(p. 4).
:param b_max: the ASP'perm bMax parameter (p. 6). A float that indicates
the amount by which a synapse'perm permanence must be
multiplied.
:param max_iterations: an integer indicating the maximum number of runs
through the set of images allowed. Pass None if no
limit is desired.
:param cycles_to_save: wait this number of iterations over the complete set
of images before saving the columns to disk.
:param output_file: file name used to save the pickled columns.
:return: a matrix *columns* of shape *shape*, created and modified
according to the BSP learning algorithm.
"""
# Initialize boost matrix.
boost = np.ones(shape=shape[:2])
part_rbuffer = partial(RingBuffer,
input_array=np.zeros(1000, dtype=np.bool),
copy=True)
# Initialize activity dictionary.
activity = defaultdict(part_rbuffer)
# Initialize columns and distances matrices.
pprint("Initializing synapses ...")
columns, distances = initialise_synapses(shape, p_connect,
connect_threshold)
pprint("Columns:")
random_rows = np.random.randint(0, shape[0], 2)
random_cols = np.random.randint(0, shape[1], 2)
pprint(columns[random_rows, random_cols])
pprint("Distances:")
pprint(distances[random_rows, random_cols])
# Calculate the inhibition_area parameter.
pprint("Calculating inhibition area ...")
inhibition_area = update_inhibition_area(columns, connect_threshold)
pprint("Inhibition area: %s" % inhibition_area)
# Calculate the desired activity in a inhibition zone.
pprint("Calculating desired activity ...")
desired_activity = desired_activity_mult * inhibition_area
pprint("Desired activity: %s" % desired_activity)
converged = False
i = 0
# While synapses are modified and the maximum number of iterations is not
# overstepped, ...
pprint("Starting learning loop ...")
start = datetime.now()
while not converged and (max_iterations is None or i < max_iterations):
# Initialize the synapses_modified array, assuming no synapses will be
# modified.
synapses_modified = np.zeros(shape=len(images), dtype=np.bool)
# For each image *image*, with index *j* in the images set, ...
for j, image, _ in read_input(images):
# According to the paper (sic):
# "minOverlap was dynamically set to be the product of the mean
# pixel intensity of the current image and the mean number of
# connected synapses for an individual column."
# This leaves unclear exactly what is meant by "mean number of
# connected synapses for an individual column"; it could be a
# historical mean or a mean over all columns, here the latter was
# chosen.
mean_conn_synapses = (columns[columns > connect_threshold].size /
(shape[2] * shape[3]))
min_overlap = image.mean() * mean_conn_synapses
# calculate the overlap of the columns with the image.
# (this is a simple count of the number of its connected synapses
# that are receiving active input (p. 3)), ...
overlap = calculate_overlap(image, columns, min_overlap,
connect_threshold, boost)
# force sparsity by inhibiting columns, ...
active, activity =\
inhibit_columns(columns, distances, inhibition_area,
overlap, activity, desired_activity)
# calculate the min_activity matrix, ...
min_activity =\
calculate_min_activity(columns, active, distances,
inhibition_area, activity,
min_activity_threshold)
# and finally, adapt the synapse's permanence values.
columns, synapses_modified[j] =\
learn_synapse_connections(columns, active, image, p_inc,
p_dec, activity, min_activity, boost,
b_inc, p_mult, connect_threshold,
distances, b_max)
# Update the inhibition_area parameter.
inhibition_area = update_inhibition_area(columns,
connect_threshold)
# Update the desired activity in a inhibition zone.
desired_activity = desired_activity_mult * inhibition_area
# Print a snapshot of the model state every 1000 images.
if j % 1000 == 0:
pprint("########## %sth image of %sth iteration ##########" %
(j+1, i+1))
elapsed = datetime.now() - start
elapsed_h = elapsed.total_seconds() // 3600
elapsed_m = (elapsed.total_seconds() // 60) % 60
elapsed_s = elapsed.seconds % 60
pprint("########## Elapsed time: %02d:%02d:%02d ##########" %
(elapsed_h, elapsed_m, elapsed_s))
pprint("Overlap:")
pprint(overlap[random_rows, random_cols])
pprint("Activity:")
for l, key in enumerate(activity.iterkeys()):
if l in random_rows:
pprint(activity[key][-100:])
pprint("Active:")
pprint(active[random_rows, random_cols])
pprint("Min activity:")
pprint(min_activity[random_rows, random_cols])
pprint("Inhibition area: %s" % inhibition_area)
pprint("Inhibition radius: %s" %
(np.sqrt(inhibition_area/np.pi),))
pprint("Desired activity: %s" % desired_activity)
pprint("Synapses modified: %s" % synapses_modified[j])
# Check if any synapses changed from connected to disconnected or
# vice-versa in the last learning cycle.
converged = test_for_convergence(synapses_modified)
pprint("Iteration %s. Number of synapses modified: %s" %
(i, synapses_modified.sum()))
if i % cycles_to_save == 0 or converged:
if output_file is not None:
with open(output_file, 'wb') as fp:
pickle.dump(columns, fp)
# Increment iterations counter.
i += 1
return columns