def dict_learn(self, imgs, feature_extractor=None, dict_learner=None):
if not self.workspace.contains("descriptors.npy"):
self.descriptors = feature_extractor(imgs)
self.workspace.save("descriptors.npy", self.descriptors)
else:
self.descriptors = self.workspace.load("descriptors.npy")
if self.mmap:
self.descriptors = get_mmap(self.descriptors)
print "descriptors extracted"
if not self.workspace.contains("dict.npy"):
dict_learner.fit(self.descriptors)
self.D = dict_learner.D
self.workspace.save("dict.npy", self.D)
else:
self.D = self.workspace.load("dict.npy")
def dict_learn(self, imgs, feature_extractor=None, dict_learner=None):
if not self.workspace.contains("descriptors.npy"):
self.descriptors = feature_extractor(imgs)
self.workspace.save("descriptors.npy", self.descriptors)
else:
self.descriptors = self.workspace.load("descriptors.npy")
if self.mmap:
self.descriptors = get_mmap(self.descriptors)
print "descriptors extracted"
if not self.workspace.contains("dict.npy"):
dict_learner.fit(self.descriptors)
self.D = dict_learner.D
self.workspace.save("dict.npy", self.D)
else:
self.D = self.workspace.load("dict.npy")
def ksvd_dict_learn(X, n_atoms, init_dict='data', sparse_coder=None,
max_iter=20, non_neg=False, approx=False, eta=None,
n_cycles=1, n_jobs=1, mmap=False, verbose=True):
"""
The K-SVD algorithm
X: the data matrix of shape (n_features,n_samples)
n_atoms: the number of atoms in the dictionary
sparse_coder: must be an instance of the sparse_coding.sparse_encoder class
approx: if true, invokes the approximate KSVD algorithm
max_iter: the maximum number of iterations
non_neg: if set to True, it uses non-negativity constraints
n_cycles: the number of updates per atom (Dictionary Update Cycles)
n_jobs: the number of CPU threads
mmap: if set to True, the algorithm applies memory mapping to save memory
"""
n_features, n_samples = X.shape
shape = (n_atoms, n_samples)
Z = np.zeros(shape)
# dictionary initialization
# track the datapoints that are not used as atoms
unused_data = []
if init_dict == 'data':
from .utils import init_dictionary
D, unused_data = init_dictionary(X, n_atoms, method=init_dict, return_unused_data=True)
else:
D = np.copy(init_dict)
if mmap:
D = get_mmap(D)
sparse_coder.mmap = True
print "dictionary initialized"
max_patience = 10
error_curr = 0
error_prev = 0
it = 0
patience = 0
approx_errors = []
while it < max_iter and patience < max_patience:
print "----------------------------"
print "iteration", it
print ""
it_start = time.time()
if verbose:
t_sparse_start = time.time()
# sparse coding
Z = sparse_coder(X, D)
if verbose:
t_sparse_duration = time.time() - t_sparse_start
print "sparse coding took", t_sparse_duration, "seconds"
t_dict_start = time.time()
# ksvd to learn the dictionary
set_openblas_threads(n_jobs)
if approx:
D, _, unused_atoms = approx_ksvd(X, D, Z, n_cycles=n_cycles)
elif non_neg:
D, _, unused_atoms = nn_ksvd(X, D, Z, n_cycles=it)
else:
D, _, unused_atoms = ksvd(X, D, Z, n_cycles=n_cycles)
set_openblas_threads(1)
if verbose:
t_dict_duration = time.time() - t_dict_start
print "K-SVD took", t_dict_duration, "seconds"
print ""
if verbose:
print "number of unused atoms:", len(unused_atoms)
# replace the unused atoms in the dictionary
for j in range(len(unused_atoms)):
# no datapoint available to be used as atom
if len(unused_data) == 0:
break
_idx = np.random.choice(unused_data, size=1)
idx = _idx[0]
D[:, unused_atoms[j]] = X[:, idx]
D[:, unused_atoms[j]] = normalize(D[:, unused_atoms[j]])
unused_data.remove(idx)
if eta is not None:
# do not force incoherence in the last iteration
if it < max_iter - 1:
# force Mutual Incoherence
D, unused_data = force_mi(D, X, Z, unused_data, eta)
if verbose:
amc = average_mutual_coherence(D)
print "average mutual coherence:", amc
it_duration = time.time() - it_start
# calculate the approximation error
error_curr = approx_error(D, Z, X, n_jobs=2)
approx_errors.append(error_curr)
if verbose:
print "error:", error_curr
print "error difference:", (error_curr - error_prev)
error_prev = error_curr
print "duration:", it_duration, "seconds"
if (it > 0) and (error_curr > 0.9 * error_prev or error_curr > error_prev):
patience += 1
it += 1
print ""
return D, Z
def projected_grad_desc(X,
n_atoms=None,
sparse_coder=None,
batch_size=None,
D_init=None,
eta=None,
mu=None,
n_epochs=None,
non_neg=False,
verbose=False,
n_jobs=1,
mmap=False):
"""
X: the data matrix of shape (n_features,n_samples)
n_atoms: the number of atoms in the dictionary
sparse_coder: must be an instance of the sparse_coding.sparse_encoder class
batch_size: the number of datapoints in each iteration
D_init: the initial dictionary. If None, we initialize it with randomly
selected datapoints.
eta: the learning rate
mu: the mutual coherence penalty
n_epochs: the number of times we iterate over the dataset
non_neg: if set to True, it uses non-negativity constraints
n_jobs: the number of CPU threads
mmap: if set to True, the algorithm applies memory mapping to save memory
Note that a large batch_size implies
faster execution but high memory overhead, while
a smaller batch_size implies
slower execution but low memory overhead
"""
# dont monitor sparse coding
sparse_coder.verbose = False
n_features, n_samples = X.shape
# initialize the dictionary
# with the dataset
if D_init is None:
D, unused_data = init_dictionary(X,
n_atoms,
method='data',
return_unused_data=True)
else:
D = D_init
print "dictionary initialized"
if mmap:
D = get_mmap(D)
batch_idx = gen_batches(n_samples, batch_size=batch_size)
n_batches = len(batch_idx)
n_iter = n_batches
n_total_iter = n_epochs * n_iter
I = np.eye(n_atoms)
if n_batches > n_iter:
print "will iterate on only {0:.2f}% of the dataset".format(
(float(n_iter) / n_batches) * 100)
if n_jobs > 1:
set_openblas_threads(n_jobs)
max_patience = 10
error_curr = 0
error_prev = 0
patience = 0
approx_errors = []
incs = []
for e in range(n_epochs):
# cycle over the batches
for i, batch in zip(range(n_iter), cycle(batch_idx)):
X_batch = X[:, batch]
# sparse coding step
Z_batch = sparse_coder(X_batch, D)
if verbose:
progress = float((e * n_iter) + i) / n_total_iter
sys.stdout.write("\r" + "dictionary learning" + "...:%3.2f%%" %
(progress * 100))
sys.stdout.flush()
# the gradient of the approximation error
grad_approx = np.dot(np.dot(D, Z_batch) - X_batch, Z_batch.T)
# the gradient of the incoherence penalty
if mu is not None and mu > 0:
grad_incoh = 2 * mu * np.dot(D, np.dot(D.T, D) - I)
else:
grad_incoh = 0
grad = grad_approx
D = D - eta * grad
# enforce non-negativity
if non_neg:
D[D < 0] = 0
# project to l2 unit sphere
D = norm_cols(D)
# sparse coding
Z = sparse_coder(X, D)
from lyssa.dict_learning.utils import average_mutual_coherence
approx_errors.append(approx_error(D, Z, X, n_jobs=n_jobs))
# replace_unused_atoms(A,unused_data,i)
if e < n_epochs - 1:
print ""
print "end of epoch {0}".format(e)
error_curr = 0
for i, batch in zip(range(n_iter), cycle(batch_idx)):
X_batch = X[:, batch]
# sparse coding step
Z_batch = sparse_coder(X_batch, D)
error_curr += approx_error(D, Z_batch, X_batch, n_jobs=n_jobs)
if verbose:
print ""
print "error:", error_curr
print "error difference:", (error_curr - error_prev)
error_prev = error_curr
if (e > 0) and (error_curr > 0.9 * error_prev
or error_curr > error_prev):
patience += 1
if patience >= max_patience:
return D
if verbose:
sys.stdout.write("\r" + "dictionary learning" + "...:%3.2f%%" % (100))
sys.stdout.flush()
print ""
return D
def online_dict_learn(X, n_atoms, sparse_coder=None, batch_size=None, A=None, B=None, D_init=None,
beta=None, n_epochs=1, verbose=False, n_jobs=1, non_neg=False, mmap=False):
"""
X: the data matrix of shape (n_features,n_samples)
n_atoms: the number of atoms in the dictionary
sparse_coder: must be an instance of the sparse_coding.sparse_encoder class
batch_size: the number of datapoints in each iteration
D_init: the initial dictionary. If None, we initialize it with randomly
selected datapoints.
eta: the learning rate
mu: the mutual coherence penalty
n_epochs: the number of times we iterate over the dataset
non_neg: if set to True, it uses non-negativity constraints
n_jobs: the number of CPU threads
mmap: if set to True, the algorithm applies memory mapping to save memory
Note that a large batch_size implies
faster execution but high memory overhead, while
a smaller batch_size implies
slower execution but low memory overhead
"""
# dont monitor sparse coding
sparse_coder.verbose = False
n_features, n_samples = X.shape
# initialize using the data
if D_init is None:
D, unused_data = init_dictionary(X, n_atoms, method='data', return_unused_data=True)
else:
D = D_init
print "dictionary initialized"
if mmap:
D = get_mmap(D)
batch_idx = gen_batches(n_samples, batch_size=batch_size)
n_batches = len(batch_idx)
n_iter = n_batches
n_total_iter = n_epochs * n_iter
_eps = np.finfo(float).eps
if n_jobs > 1:
set_openblas_threads(n_jobs)
if A is None and B is None:
A = np.zeros((n_atoms, n_atoms))
B = np.zeros((n_features, n_atoms))
if beta is None:
# create a sequence that converges to one
beta = np.linspace(0, 1, num=n_iter)
else:
beta = np.zeros(n_iter) + beta
max_patience = 10
error_curr = 0
error_prev = 0
patience = 0
approx_errors = []
incs = []
for e in range(n_epochs):
# cycle over the batches
for i, batch in zip(range(n_iter), cycle(batch_idx)):
X_batch = X[:, batch]
# sparse coding step
Z_batch = sparse_coder(X_batch, D)
# update A and B
A = beta[i] * A + fast_dot(Z_batch, Z_batch.T)
B = beta[i] * B + fast_dot(X_batch, Z_batch.T)
if verbose:
progress = float((e * n_iter) + i) / n_total_iter
sys.stdout.write("\r" + "dictionary learning" + "...:%3.2f%%" % (progress * 100))
sys.stdout.flush()
DA = fast_dot(D, A)
# this part could also be parallelized w.r.t the atoms
for k in xrange(n_atoms):
D[:, k] = (1 / (A[k, k] + _eps)) * (B[:, k] - DA[:, k]) + D[:, k]
# enforce non-negativity constraints
if non_neg:
D[D < 0] = 0
D = norm_cols(D)
# replace_unused_atoms(A,unused_data,i)
if e < n_epochs - 1:
if patience >= max_patience:
return D, A, B
print ""
print "end of epoch {0}".format(e)
error_curr = 0
for i, batch in zip(range(n_iter), cycle(batch_idx)):
X_batch = X[:, batch]
# sparse coding step
Z_batch = sparse_coder(X_batch, D)
error_curr += approx_error(D, Z_batch, X_batch, n_jobs=n_jobs)
if verbose:
print ""
print "error:", error_curr
print "error difference:", (error_curr - error_prev)
error_prev = error_curr
if (e > 0) and (error_curr > 0.9 * error_prev or error_curr > error_prev):
patience += 1
if verbose:
sys.stdout.write("\r" + "dictionary learning" + "...:%3.2f%%" % (100))
sys.stdout.flush()
print ""
return D, A, B
def ksvd_dict_learn(X, n_atoms, init_dict='data', sparse_coder=None,
max_iter=20, non_neg=False, approx=False, eta=None,
n_cycles=1, n_jobs=1, mmap=False, verbose=True):
"""
The K-SVD algorithm
X: the data matrix of shape (n_features,n_samples)
n_atoms: the number of atoms in the dictionary
sparse_coder: must be an instance of the sparse_coding.sparse_encoder class
approx: if true, invokes the approximate KSVD algorithm
max_iter: the maximum number of iterations
non_neg: if set to True, it uses non-negativity constraints
n_cycles: the number of updates per atom (Dictionary Update Cycles)
n_jobs: the number of CPU threads
mmap: if set to True, the algorithm applies memory mapping to save memory
"""
n_features, n_samples = X.shape
shape = (n_atoms, n_samples)
Z = np.zeros(shape)
# dictionary initialization
# track the datapoints that are not used as atoms
unused_data = []
if init_dict == 'data':
from .utils import init_dictionary
D, unused_data = init_dictionary(X, n_atoms, method=init_dict, return_unused_data=True)
else:
D = np.copy(init_dict)
if mmap:
D = get_mmap(D)
sparse_coder.mmap = True
print "dictionary initialized"
max_patience = 10
error_curr = 0
error_prev = 0
it = 0
patience = 0
approx_errors = []
while it < max_iter and patience < max_patience:
print "----------------------------"
print "iteration", it
print ""
it_start = time.time()
if verbose:
t_sparse_start = time.time()
# sparse coding
Z = sparse_coder(X, D)
if verbose:
t_sparse_duration = time.time() - t_sparse_start
print "sparse coding took", t_sparse_duration, "seconds"
t_dict_start = time.time()
# ksvd to learn the dictionary
set_openblas_threads(n_jobs)
if approx:
D, _, unused_atoms = approx_ksvd(X, D, Z, n_cycles=n_cycles)
elif non_neg:
D, _, unused_atoms = nn_ksvd(X, D, Z, n_cycles=it)
else:
D, _, unused_atoms = ksvd(X, D, Z, n_cycles=n_cycles)
set_openblas_threads(1)
if verbose:
t_dict_duration = time.time() - t_dict_start
print "K-SVD took", t_dict_duration, "seconds"
print ""
if verbose:
print "number of unused atoms:", len(unused_atoms)
# replace the unused atoms in the dictionary
for j in range(len(unused_atoms)):
# no datapoint available to be used as atom
if len(unused_data) == 0:
break
_idx = np.random.choice(unused_data, size=1)
idx = _idx[0]
D[:, unused_atoms[j]] = X[:, idx]
D[:, unused_atoms[j]] = normalize(D[:, unused_atoms[j]])
unused_data.remove(idx)
if eta is not None:
# do not force incoherence in the last iteration
if it < max_iter - 1:
# force Mutual Incoherence
D, unused_data = force_mi(D, X, Z, unused_data, eta)
if verbose:
amc = average_mutual_coherence(D)
print "average mutual coherence:", amc
it_duration = time.time() - it_start
# calculate the approximation error
error_curr = approx_error(D, Z, X, n_jobs=2)
approx_errors.append(error_curr)
if verbose:
print "error:", error_curr
print "error difference:", (error_curr - error_prev)
error_prev = error_curr
print "duration:", it_duration, "seconds"
if (it > 0) and (error_curr > 0.9 * error_prev or error_curr > error_prev):
patience += 1
it += 1
print ""
return D, Z
def lc_ksvd(X,
y,
D,
Q,
alpha=1,
beta=1,
lambda1=1,
lambda2=1,
sparse_coder=None,
max_iter=2,
approx=False,
mmap=False,
verbose=False,
n_jobs=1):
"""
X: the data matrix with shape (n_features,n_samples)
y: the vector that contains the label of each datapoint
Q: a matrix with shape (n_atoms,n_samples). The element Q_{k,i} is 1 if the ith datapoint and the k atom belong to the same class
lambda1: the regularizer for the W matrix i.e lambda1 * ||W||_{2}
lambda2: the regularizer for the transformation matrix G i.e lambda2 * ||G||_{2}
alpha: the weight we assign for sparse code discrimination
beta: is the weight we assign for correct classification: beta*||H - WZ||_{2}
"""
n_classes = len(set(y))
n_atoms = D.shape[1]
n_features, n_samples = X.shape
Z = np.zeros((n_atoms, n_samples))
# create the class label matrix
# H is the class label matrix which has a
# datapoint in each column with H_{c,i}=1 if
# the ith datapoint belongs to the cth class
H = np.zeros((n_classes, n_samples)).astype(int)
for i in xrange(n_samples):
H[y[i], i] = 1
if n_jobs > 1:
set_openblas_threads(n_jobs)
# classifier parameter initialization
I = np.eye(n_atoms)
# W_{c,:} are the parameters of the linear classifier for the cth class
W = np.dot(inv(np.dot(Z, Z.T) + lambda1 * I), np.dot(Z, H.T)).T
# The matrix G forces the sparse codes to be discriminative and approximate the matrix Q,
# and has shape (n_atoms,n_atoms)
G = np.dot(inv(np.dot(Z, Z.T) + lambda2 * I), np.dot(Z, Q.T)).T
# stack the data matrix X with class label matrix H
# and matrix Q
_X = np.vstack((X, np.sqrt(alpha) * Q))
_X = np.vstack((_X, np.sqrt(beta) * H))
if mmap:
_X = get_mmap(_X)
_normalizer = np.array(
[np.sqrt(np.dot(D[:, j], D[:, j])) for j in range(D.shape[1])])
D = D / _normalizer
G = G / _normalizer
W = W / _normalizer
# stack the dictionary D with the weight matrix W
# and matrix G
_D = np.vstack((D, np.sqrt(alpha) * G))
_D = np.vstack((_D, np.sqrt(beta) * W))
if mmap:
_D = get_mmap(_D)
if verbose:
error_curr = 0
error_prev = 0
for it in range(max_iter):
print "iteration", it
it_start = time.time()
if verbose:
t_sparse_start = time.time()
# sparse coding
Z = sparse_coder(X, D)
if verbose:
t_sparse_duration = time.time() - t_sparse_start
print "\nsparse coding took", t_sparse_duration, "seconds"
t_dict_start = time.time()
_D, _, unused_atoms = ksvd(_X, _D, Z, verbose=True)
if verbose:
t_dict_duration = time.time() - t_dict_start
print "\nK-SVD took", t_dict_duration, "seconds"
if verbose:
print "number of unused atoms:", len(unused_atoms)
D = _D[:n_features, :]
G = _D[n_features:n_features + n_atoms, :]
W = _D[n_features + n_atoms:, :]
_normalizer = np.array(
[np.sqrt(np.dot(D[:, j], D[:, j])) for j in range(D.shape[1])])
D = D / _normalizer
G = G / _normalizer
W = W / _normalizer
# stack the dictionary D with the weight matrix W
# and matrix G
_D = np.vstack((D, np.sqrt(alpha) * G))
_D = np.vstack((_D, np.sqrt(beta) * W))
it_duration = time.time() - it_start
if verbose:
# calculate the approximation error
error_curr = approx_error(D, Z, X, n_jobs=2)
print "error:", error_curr
print "error difference:", (error_curr - error_prev)
n_correct = np.array([
y[i] == np.argmax(np.dot(W, Z[:, i]))
for i in range(Z.shape[1])
]).nonzero()[0].size
class_acc = n_correct / float(n_samples)
print "classification accuracy", class_acc
error_prev = error_curr
print "duration:", it_duration, "seconds"
print "----------------------"
return D, Z, W
def online_dict_learn(X, n_atoms, sparse_coder=None, batch_size=None, A=None, B=None, D_init=None,
beta=None, n_epochs=1, verbose=False, n_jobs=1, non_neg=False, mmap=False):
"""
X: the data matrix of shape (n_features,n_samples)
n_atoms: the number of atoms in the dictionary
sparse_coder: must be an instance of the sparse_coding.sparse_encoder class
batch_size: the number of datapoints in each iteration
D_init: the initial dictionary. If None, we initialize it with randomly
selected datapoints.
eta: the learning rate
mu: the mutual coherence penalty
n_epochs: the number of times we iterate over the dataset
non_neg: if set to True, it uses non-negativity constraints
n_jobs: the number of CPU threads
mmap: if set to True, the algorithm applies memory mapping to save memory
Note that a large batch_size implies
faster execution but high memory overhead, while
a smaller batch_size implies
slower execution but low memory overhead
"""
# dont monitor sparse coding
sparse_coder.verbose = False
n_features, n_samples = X.shape
# initialize using the data
if D_init is None:
D, unused_data = init_dictionary(X, n_atoms, method='data', return_unused_data=True)
else:
D = D_init
print "dictionary initialized"
if mmap:
D = get_mmap(D)
batch_idx = gen_batches(n_samples, batch_size=batch_size)
n_batches = len(batch_idx)
n_iter = n_batches
n_total_iter = n_epochs * n_iter
_eps = np.finfo(float).eps
if n_jobs > 1:
set_openblas_threads(n_jobs)
if A is None and B is None:
A = np.zeros((n_atoms, n_atoms))
B = np.zeros((n_features, n_atoms))
if beta is None:
# create a sequence that converges to one
beta = np.linspace(0, 1, num=n_iter)
else:
beta = np.zeros(n_iter) + beta
max_patience = 10
error_curr = 0
error_prev = 0
patience = 0
approx_errors = []
incs = []
for e in range(n_epochs):
# cycle over the batches
for i, batch in zip(range(n_iter), cycle(batch_idx)):
X_batch = X[:, batch]
# sparse coding step
Z_batch = sparse_coder(X_batch, D)
# update A and B
A = beta[i] * A + fast_dot(Z_batch, Z_batch.T)
B = beta[i] * B + fast_dot(X_batch, Z_batch.T)
if verbose:
progress = float((e * n_iter) + i) / n_total_iter
sys.stdout.write("\r" + "dictionary learning" + "...:%3.2f%%" % (progress * 100))
sys.stdout.flush()
DA = fast_dot(D, A)
# this part could also be parallelized w.r.t the atoms
for k in xrange(n_atoms):
D[:, k] = (1 / (A[k, k] + _eps)) * (B[:, k] - DA[:, k]) + D[:, k]
# enforce non-negativity constraints
if non_neg:
D[D < 0] = 0
D = norm_cols(D)
# replace_unused_atoms(A,unused_data,i)
if e < n_epochs - 1:
if patience >= max_patience:
return D, A, B
print ""
print "end of epoch {0}".format(e)
error_curr = 0
for i, batch in zip(range(n_iter), cycle(batch_idx)):
X_batch = X[:, batch]
# sparse coding step
Z_batch = sparse_coder(X_batch, D)
error_curr += approx_error(D, Z_batch, X_batch, n_jobs=n_jobs)
if verbose:
print ""
print "error:", error_curr
print "error difference:", (error_curr - error_prev)
error_prev = error_curr
if (e > 0) and (error_curr > 0.9 * error_prev or error_curr > error_prev):
patience += 1
if verbose:
sys.stdout.write("\r" + "dictionary learning" + "...:%3.2f%%" % (100))
sys.stdout.flush()
print ""
return D, A, B
def lc_ksvd(X, y, D, Q, alpha=1, beta=1, lambda1=1, lambda2=1,
sparse_coder=None, max_iter=2, approx=False, mmap=False, verbose=False, n_jobs=1):
"""
X: the data matrix with shape (n_features,n_samples)
y: the vector that contains the label of each datapoint
Q: a matrix with shape (n_atoms,n_samples). The element Q_{k,i} is 1 if the ith datapoint and the k atom belong to the same class
lambda1: the regularizer for the W matrix i.e lambda1 * ||W||_{2}
lambda2: the regularizer for the transformation matrix G i.e lambda2 * ||G||_{2}
alpha: the weight we assign for sparse code discrimination
beta: is the weight we assign for correct classification: beta*||H - WZ||_{2}
"""
n_classes = len(set(y))
n_atoms = D.shape[1]
n_features, n_samples = X.shape
Z = np.zeros((n_atoms, n_samples))
# create the class label matrix
# H is the class label matrix which has a
# datapoint in each column with H_{c,i}=1 if
# the ith datapoint belongs to the cth class
H = np.zeros((n_classes, n_samples)).astype(int)
for i in xrange(n_samples):
H[y[i], i] = 1
if n_jobs > 1:
set_openblas_threads(n_jobs)
# classifier parameter initialization
I = np.eye(n_atoms)
# W_{c,:} are the parameters of the linear classifier for the cth class
W = np.dot(inv(np.dot(Z, Z.T) + lambda1 * I), np.dot(Z, H.T)).T
# The matrix G forces the sparse codes to be discriminative and approximate the matrix Q,
# and has shape (n_atoms,n_atoms)
G = np.dot(inv(np.dot(Z, Z.T) + lambda2 * I), np.dot(Z, Q.T)).T
# stack the data matrix X with class label matrix H
# and matrix Q
_X = np.vstack((X, np.sqrt(alpha) * Q))
_X = np.vstack((_X, np.sqrt(beta) * H))
if mmap:
_X = get_mmap(_X)
_normalizer = np.array([np.sqrt(np.dot(D[:, j], D[:, j])) for j in range(D.shape[1])])
D = D / _normalizer
G = G / _normalizer
W = W / _normalizer
# stack the dictionary D with the weight matrix W
# and matrix G
_D = np.vstack((D, np.sqrt(alpha) * G))
_D = np.vstack((_D, np.sqrt(beta) * W))
if mmap:
_D = get_mmap(_D)
if verbose:
error_curr = 0
error_prev = 0
for it in range(max_iter):
print "iteration", it
it_start = time.time()
if verbose:
t_sparse_start = time.time()
# sparse coding
Z = sparse_coder(X, D)
if verbose:
t_sparse_duration = time.time() - t_sparse_start
print "\nsparse coding took", t_sparse_duration, "seconds"
t_dict_start = time.time()
_D, _, unused_atoms = ksvd(_X, _D, Z, verbose=True)
if verbose:
t_dict_duration = time.time() - t_dict_start
print "\nK-SVD took", t_dict_duration, "seconds"
if verbose:
print "number of unused atoms:", len(unused_atoms)
D = _D[:n_features, :]
G = _D[n_features:n_features + n_atoms, :]
W = _D[n_features + n_atoms:, :]
_normalizer = np.array([np.sqrt(np.dot(D[:, j], D[:, j])) for j in range(D.shape[1])])
D = D / _normalizer
G = G / _normalizer
W = W / _normalizer
# stack the dictionary D with the weight matrix W
# and matrix G
_D = np.vstack((D, np.sqrt(alpha) * G))
_D = np.vstack((_D, np.sqrt(beta) * W))
it_duration = time.time() - it_start
if verbose:
# calculate the approximation error
error_curr = approx_error(D, Z, X, n_jobs=2)
print "error:", error_curr
print "error difference:", (error_curr - error_prev)
n_correct = np.array([y[i] == np.argmax(np.dot(W, Z[:, i]))
for i in range(Z.shape[1])]).nonzero()[0].size
class_acc = n_correct / float(n_samples)
print "classification accuracy", class_acc
error_prev = error_curr
print "duration:", it_duration, "seconds"
print "----------------------"
return D, Z, W
def projected_grad_desc(X, n_atoms=None, sparse_coder=None, batch_size=None, D_init=None,
eta=None, mu=None, n_epochs=None, non_neg=False, verbose=False, n_jobs=1, mmap=False):
"""
X: the data matrix of shape (n_features,n_samples)
n_atoms: the number of atoms in the dictionary
sparse_coder: must be an instance of the sparse_coding.sparse_encoder class
batch_size: the number of datapoints in each iteration
D_init: the initial dictionary. If None, we initialize it with randomly
selected datapoints.
eta: the learning rate
mu: the mutual coherence penalty
n_epochs: the number of times we iterate over the dataset
non_neg: if set to True, it uses non-negativity constraints
n_jobs: the number of CPU threads
mmap: if set to True, the algorithm applies memory mapping to save memory
Note that a large batch_size implies
faster execution but high memory overhead, while
a smaller batch_size implies
slower execution but low memory overhead
"""
if eta is None:
raise ValueError('Must specify learning rate.')
# don't monitor sparse coding
sparse_coder.verbose = False
n_features, n_samples = X.shape
# initialize the dictionary
# with the dataset
if D_init is None:
D, unused_data = init_dictionary(X, n_atoms, method='data', return_unused_data=True)
else:
D = D_init
print "dictionary initialized"
if mmap:
D = get_mmap(D)
batch_idx = gen_batches(n_samples, batch_size=batch_size)
n_batches = len(batch_idx)
n_iter = n_batches
n_total_iter = n_epochs * n_iter
I = np.eye(n_atoms)
if n_batches > n_iter:
print "will iterate on only {0:.2f}% of the dataset".format((float(n_iter) / n_batches) * 100)
if n_jobs > 1:
set_openblas_threads(n_jobs)
max_patience = 10
error_prev = 0
patience = 0
approx_errors = []
for e in range(n_epochs):
# cycle over the batches
for i, batch in zip(range(n_iter), cycle(batch_idx)):
X_batch = X[:, batch]
# sparse coding step
Z_batch = sparse_coder(X_batch, D)
if verbose:
progress = float((e * n_iter) + i) / n_total_iter
sys.stdout.write("\r" + "dictionary learning" + "...:%3.2f%%" % (progress * 100))
sys.stdout.flush()
# the gradient of the approximation error
grad_approx = np.dot(np.dot(D, Z_batch) - X_batch, Z_batch.T)
# the gradient of the incoherence penalty
if mu is not None and mu > 0:
grad_incoh = 2 * mu * np.dot(D, np.dot(D.T, D) - I)
else:
grad_incoh = 0
grad = grad_approx
D = D - (eta * grad) + grad_incoh
# enforce non-negativity
if non_neg:
D[D < 0] = 0
# project to l2 unit sphere
D = norm_cols(D)
# sparse coding
Z = sparse_coder(X, D)
#replace_unused_atoms(A,unused_data,i)
if e < n_epochs - 1:
print ""
print "end of epoch {0}".format(e)
error_curr = 0
for i, batch in zip(range(n_iter), cycle(batch_idx)):
X_batch = X[:, batch]
# sparse coding step
Z_batch = sparse_coder(X_batch, D)
error_curr += approx_error(D, Z_batch, X_batch, n_jobs=n_jobs)
if verbose:
print ""
print "error:", error_curr
print "error difference:", (error_curr - error_prev)
error_prev = error_curr
if (e > 0) and (error_curr > 0.9 * error_prev or error_curr > error_prev):
patience += 1
if patience >= max_patience:
return D
if verbose:
sys.stdout.write("\r" + "dictionary learning" + "...:%3.2f%%" % (100))
sys.stdout.flush()
print ""
return D