class SiameseNet:
def __init__(self, inputs, arch, siam_reg, y_true):
self.orig_inputs = inputs
# set up inputs
self.inputs = {
'A': inputs['Unlabeled'],
'B': Input(shape=inputs['Unlabeled'].get_shape().as_list()[1:]),
'Labeled': inputs['Labeled'],
}
self.y_true = y_true
# generate layers
self.layers = []
self.layers += make_layer_list(arch, 'siamese', siam_reg)
# create the siamese net
self.outputs = stack_layers(self.inputs, self.layers)
# add the distance layer
self.distance = Lambda(costs.euclidean_distance,
output_shape=costs.eucl_dist_output_shape)(
[self.outputs['A'], self.outputs['B']])
#create the distance model for training
self.net = Model([self.inputs['A'], self.inputs['B']], self.distance)
# compile the siamese network
self.net.compile(loss=costs.get_contrastive_loss(m_neg=1, m_pos=0.05),
optimizer='rmsprop')
def train(self, pairs_train, dist_train, pairs_val, dist_val, lr, drop,
patience, num_epochs, batch_size):
# create handler for early stopping and learning rate scheduling
self.lh = LearningHandler(lr=lr,
drop=drop,
lr_tensor=self.net.optimizer.lr,
patience=patience)
# initialize the training generator
train_gen_ = train_gen(pairs_train, dist_train, batch_size)
# format the validation data for keras
validation_data = ([pairs_val[:, 0], pairs_val[:, 1]], dist_val)
# compute the steps per epoch
steps_per_epoch = int(len(pairs_train) / batch_size)
# train the network
hist = self.net.fit_generator(train_gen_,
epochs=num_epochs,
validation_data=validation_data,
steps_per_epoch=steps_per_epoch,
callbacks=[self.lh])
return hist
def predict(self, x, batch_sizes):
# compute the siamese embeddings of the input data
return train.predict(self.outputs['A'],
x_unlabeled=x,
inputs=self.orig_inputs,
y_true=self.y_true,
batch_sizes=batch_sizes)
class SiameseNet(object):
"""Class for Siamese Network."""
def __init__(self, inputs, arch, siam_reg, main_path, y_true):
self.orig_inputs = inputs
# set up inputs
self.inputs = {
'A': inputs['Unlabeled'],
'B': Input(shape=inputs['Unlabeled'].get_shape().as_list()[1:]),
'Labeled': inputs['Labeled'],
}
self.main_path = os.path.join(main_path, 'siemese/')
self.y_true = y_true
# generate layers
self.layers = []
self.layers += util.make_layer_list(arch, 'siamese', siam_reg)
# create the siamese net
self.outputs = stack_layers(self.inputs, self.layers)
# add the distance layer
self.distance = Lambda(affinities.euclidean_distance,
output_shape=affinities.eucl_dist_output_shape)(
[self.outputs['A'], self.outputs['B']])
# create the distance model for training
self.net = Model([self.inputs['A'], self.inputs['B']], self.distance)
# compile the siamese network
self.net.compile(loss=affinities.get_contrastive_loss(m_neg=1,
m_pos=0.05),
optimizer='rmsprop')
def train(self,
pairs_train,
dist_train,
pairs_val,
dist_val,
lr,
drop,
patience,
num_epochs,
batch_size,
dset,
load=True):
"""Train the Siamese Network."""
if load:
# load weights into model
output_path = os.path.join(self.main_path, dset)
load_model(self.net, output_path, '_siamese')
return
# create handler for early stopping and learning rate scheduling
self.lh = util.LearningHandler(lr=lr,
drop=drop,
lr_tensor=self.net.optimizer.lr,
patience=patience)
# initialize the training generator
train_gen_ = util.train_gen(pairs_train, dist_train, batch_size)
# format the validation data for keras
validation_data = ([pairs_val[:, 0], pairs_val[:, 1]], dist_val)
# compute the steps per epoch
steps_per_epoch = int(len(pairs_train) / batch_size)
# train the network
self.net.fit_generator(train_gen_,
epochs=num_epochs,
validation_data=validation_data,
steps_per_epoch=steps_per_epoch,
callbacks=[self.lh])
model_json = self.net.to_json()
output_path = os.path.join(self.main_path, dset)
save_model(self.net, model_json, output_path, '_siamese')
def predict(self, x, batch_sizes):
# compute the siamese embeddings of the input data
return train.predict(self.outputs['A'],
x_unlabeled=x,
inputs=self.orig_inputs,
y_true=self.y_true,
batch_sizes=batch_sizes)
model.summary()
# loop over all layers in the base model and freeze them so they will *not* be updated during the first training process
for layer in baseModel.layers:
layer.trainable = False
# compile our model
print("[INFO] compiling model...")
opt = Adam(lr=INIT_LR, decay=DEC)
model.compile(loss="binary_crossentropy", optimizer=opt, metrics=["accuracy"])
# train the head of the network
print("[INFO] training head...")
H = model.fit_generator(trainAug.flow(trainX, trainY, batch_size=BS),
steps_per_epoch=len(trainX) // BS,
validation_data=(testX, testY),
validation_steps=len(testX) // BS,
epochs=EPOCHS)
# make predictions on the testing set
print("[INFO] evaluating network...")
predIdxs = model.predict(testX, batch_size=BS)
# for each image in the testing set we need to find the index of the label with corresponding largest predicted probability
predIdxs = np.argmax(predIdxs, axis=1)
# show a nicely formatted classification report
print(
classification_report(testY.argmax(axis=1),
predIdxs,
target_names=lb.classes_))
