class HTRModel:
def __init__(self,
architecture,
input_size,
vocab_size,
greedy=False,
beam_width=10,
top_paths=1):
"""
Initialization of a HTR Model.
:param
architecture: option of the architecture model to build and compile
greedy, beam_width, top_paths: Parameters of the CTC decoding
(see ctc decoding tensorflow for more details)
"""
self.architecture = globals()[architecture]
self.input_size = input_size
self.vocab_size = vocab_size
self.model = None
self.greedy = greedy
self.beam_width = beam_width
self.top_paths = max(1, top_paths)
def summary(self, output=None, target=None):
"""Show/Save model structure (summary)"""
self.model.summary()
if target is not None:
os.makedirs(output, exist_ok=True)
with open(os.path.join(output, target), "w") as f:
with redirect_stdout(f):
self.model.summary()
def load_checkpoint(self, target):
""" Load a model with checkpoint file"""
if os.path.isfile(target):
if self.model is None:
self.compile()
self.model.load_weights(target)
def get_callbacks(self, logdir, checkpoint, monitor="val_loss", verbose=0):
"""Setup the list of callbacks for the model"""
callbacks = [
CSVLogger(
filename=os.path.join(logdir, "epochs.log"),
separator=";",
append=True),
TensorBoard(
log_dir=logdir,
histogram_freq=10,
profile_batch=0,
write_graph=True,
write_images=False,
update_freq="epoch"),
ModelCheckpoint(
filepath=checkpoint,
monitor=monitor,
save_best_only=True,
save_weights_only=True,
verbose=verbose),
EarlyStopping(
monitor=monitor,
min_delta=1e-8,
patience=20,
restore_best_weights=True,
verbose=verbose),
ReduceLROnPlateau(
monitor=monitor,
min_delta=1e-8,
factor=0.2,
patience=15,
verbose=verbose)
]
return callbacks
def compile(self, learning_rate=None):
"""
Configures the HTR Model for training/predict.
:param optimizer: optimizer for training
"""
# define inputs, outputs and optimizer of the chosen architecture
outs = self.architecture(self.input_size, self.vocab_size + 1, learning_rate)
inputs, outputs, optimizer = outs
# create and compile
self.model = Model(inputs=inputs, outputs=outputs)
self.model.compile(optimizer=optimizer, loss=self.ctc_loss_lambda_func)
def fit(self,
x=None,
y=None,
batch_size=None,
epochs=1,
verbose=1,
callbacks=None,
validation_split=0.0,
validation_data=None,
shuffle=True,
class_weight=None,
sample_weight=None,
initial_epoch=0,
steps_per_epoch=None,
validation_steps=None,
validation_freq=1,
max_queue_size=10,
workers=1,
use_multiprocessing=False,
**kwargs):
"""
Model training on data yielded (fit function has support to generator).
A fit() abstration function of TensorFlow 2.
Provide x parameter of the form: yielding (x, y, sample_weight).
:param: See tensorflow.keras.Model.fit()
:return: A history object
"""
out = self.model.fit(x=x, y=y, batch_size=batch_size, epochs=epochs, verbose=verbose,
callbacks=callbacks, validation_split=validation_split,
validation_data=validation_data, shuffle=shuffle,
class_weight=class_weight, sample_weight=sample_weight,
initial_epoch=initial_epoch, steps_per_epoch=steps_per_epoch,
validation_steps=validation_steps, validation_freq=validation_freq,
max_queue_size=max_queue_size, workers=workers,
use_multiprocessing=use_multiprocessing, **kwargs)
return out
def predict(self,
x,
batch_size=None,
verbose=0,
steps=1,
callbacks=None,
max_queue_size=10,
workers=1,
use_multiprocessing=False,
ctc_decode=True):
"""
Model predicting on data yielded (predict function has support to generator).
A predict() abstration function of TensorFlow 2.
Provide x parameter of the form: yielding [x].
:param: See tensorflow.keras.Model.predict()
:return: raw data on `ctc_decode=False` or CTC decode on `ctc_decode=True` (both with probabilities)
"""
self.model._make_predict_function()
if verbose == 1:
print("Model Predict")
out = self.model.predict(x=x, batch_size=batch_size, verbose=verbose, steps=steps,
callbacks=callbacks, max_queue_size=max_queue_size,
workers=workers, use_multiprocessing=use_multiprocessing)
if not ctc_decode:
return np.log(out)
steps_done = 0
if verbose == 1:
print("CTC Decode")
progbar = Progbar(target=steps)
batch_size = int(np.ceil(len(out) / steps))
input_length = len(max(out, key=len))
predicts, probabilities = [], []
while steps_done < steps:
index = steps_done * batch_size
until = index + batch_size
x_test = np.asarray(out[index:until])
x_test_len = np.asarray([input_length for _ in range(len(x_test))])
decode, log = K.ctc_decode(x_test,
x_test_len,
greedy=self.greedy,
beam_width=self.beam_width,
top_paths=self.top_paths)
probabilities.extend([np.exp(x) for x in log])
decode = [[[int(p) for p in x if p != -1] for x in y] for y in decode]
predicts.extend(np.swapaxes(decode, 0, 1))
steps_done += 1
if verbose == 1:
progbar.update(steps_done)
return (predicts, probabilities)
@staticmethod
def ctc_loss_lambda_func(y_true, y_pred):
"""Function for computing the CTC loss"""
if len(y_true.shape) > 2:
y_true = tf.squeeze(y_true)
input_length = tf.math.reduce_sum(y_pred, axis=-1, keepdims=False)
input_length = tf.math.reduce_sum(input_length, axis=-1, keepdims=True)
label_length = tf.math.count_nonzero(y_true, axis=-1, keepdims=True, dtype="int64")
loss = K.ctc_batch_cost(y_true, y_pred, input_length, label_length)
loss = tf.reduce_mean(loss)
return loss
class HTRModel:
def __init__(self,
architecture,
input_size,
vocab_size,
greedy=False,
beam_width=100,
top_paths=1):
"""
Initialization of a HTR Model.
:param
architecture: option of the architecture model to build and compile
greedy, beam_width, top_paths: Parameters of the CTC decoding
(see ctc decoding tensorflow for more details)
"""
self.architecture = globals()[architecture]
self.input_size = input_size
self.vocab_size = vocab_size
self.greedy = greedy
self.beam_width = beam_width
self.top_paths = max(1, top_paths)
self.model = None
self.model_infer = None
def summary(self, output=None, target=None):
"""Show/Save model structure (summary)"""
self.model.summary()
if target is not None:
os.makedirs(output, exist_ok=True)
with open(os.path.join(output, target), "w") as f:
with redirect_stdout(f):
self.model.summary()
def load_checkpoint(self, target):
""" Load a model with checkpoint file"""
if os.path.isfile(target):
if self.model is None:
self.compile()
self.model.load_weights(target)
self.model_infer.load_weights(target)
def get_callbacks(self, logdir, checkpoint, monitor="val_loss", verbose=0):
"""Setup the list of callbacks for the model"""
callbacks = [
CSVLogger(filename=os.path.join(logdir, "epochs.log"),
separator=";",
append=True),
TensorBoard(log_dir=logdir,
histogram_freq=10,
profile_batch=0,
write_graph=True,
write_images=False,
update_freq="epoch"),
ModelCheckpoint(filepath=checkpoint,
monitor=monitor,
save_best_only=True,
save_weights_only=True,
verbose=verbose),
EarlyStopping(monitor=monitor,
min_delta=1e-8,
patience=20,
restore_best_weights=True,
verbose=verbose),
ReduceLROnPlateau(monitor=monitor,
min_delta=1e-8,
factor=0.2,
patience=12,
verbose=verbose)
]
return callbacks
def compile(self, learning_rate=None):
"""
Configures the HTR Model for training/predict.
There are 2 Tensorflow Keras models:
- one for training
- one for predicting (with/without CTC decode)
Lambda layers are used to compute:
- the CTC loss function
- the CTC decoding
:param optimizer: The optimizer used during training
"""
# define inputs, outputs and optimizer of the chosen architecture
outs = self.architecture(self.input_size, self.vocab_size + 1,
learning_rate)
inputs, outputs, optimizer = outs
# others inputs for the CTC approach
labels = Input(name="labels", shape=[None])
input_length = Input(name="input_length", shape=[1])
label_length = Input(name="label_length", shape=[1])
# lambda layer for computing the loss function
loss_out = Lambda(self.ctc_loss_lambda_func,
output_shape=(1, ),
name="CTCloss")(
[outputs, labels, input_length, label_length])
# lambda layer for the raw data function
out_raw_dense = Lambda(lambda y_pred: y_pred[0],
output_shape=(None, None),
name="NoCTCdecode",
dtype="float32")([outputs, input_length])
# create Tensorflow Keras models
self.model = Model(inputs=[inputs, labels, input_length, label_length],
outputs=loss_out)
self.model_infer = Model(inputs=[inputs, input_length],
outputs=out_raw_dense)
# compile models
self.model.compile(loss={
"CTCloss": lambda yt, yp: yp
},
optimizer=optimizer)
self.model_infer.compile(loss={
"NoCTCdecode": lambda yt, yp: yp
},
optimizer=optimizer)
def fit(self,
x=None,
y=None,
batch_size=None,
epochs=1,
verbose=1,
callbacks=None,
validation_split=0.0,
validation_data=None,
shuffle=True,
class_weight=None,
sample_weight=None,
initial_epoch=0,
steps_per_epoch=None,
validation_steps=None,
validation_freq=1,
max_queue_size=10,
workers=1,
use_multiprocessing=False,
**kwargs):
"""
Model training on data yielded (fit function has support to generator).
A fit() abstration function of TensorFlow 2 using the model_train.
Provide x parameter of the form: (x, y, sample_weight), where:
x: inputs = {
"input": x_valid,
"labels": y_valid,
"input_length": x_valid_len,
"label_length": y_valid_len
}
y: output = {
"CTCloss": np.zeros(self.batch_size, dtype=int)
}
sample_weight: []
yielding: (inputs, output, [])
:param: See tensorflow.keras.Model.fit()
:return: A history object
"""
out = self.model.fit(x=x,
y=y,
batch_size=batch_size,
epochs=epochs,
verbose=verbose,
callbacks=callbacks,
validation_split=validation_split,
validation_data=validation_data,
shuffle=shuffle,
class_weight=class_weight,
sample_weight=sample_weight,
initial_epoch=initial_epoch,
steps_per_epoch=steps_per_epoch,
validation_steps=validation_steps,
validation_freq=validation_freq,
max_queue_size=max_queue_size,
workers=workers,
use_multiprocessing=use_multiprocessing,
**kwargs)
return out
def predict(self,
x,
batch_size=None,
verbose=0,
steps=1,
callbacks=None,
max_queue_size=10,
workers=1,
use_multiprocessing=False,
ctc_decode=True):
"""
Model predicting on data yielded (predict function has support to generator).
A predict() abstration function of TensorFlow 2 using the model_infer.
Provide x parameter of the form: [x_test, x_test_len]
:param: See tensorflow.keras.Model.predict()
:return: raw data on `ctc_decode=False` or CTC decode on `ctc_decode=True` (both with probabilities)
"""
self.model_infer._make_predict_function()
if verbose == 1:
print("Model Predict")
out = self.model_infer.predict(x=x,
batch_size=batch_size,
verbose=verbose,
steps=steps,
callbacks=callbacks,
max_queue_size=max_queue_size,
workers=workers,
use_multiprocessing=use_multiprocessing)
if not ctc_decode:
return out
steps_done = 0
if verbose == 1:
print("CTC Decode")
progbar = Progbar(target=steps)
batch_size = len(out) // steps
max_text_length = len(max(out, key=len))
x_test_len = np.asarray([max_text_length for _ in range(batch_size)])
predicts, probabilities = [], []
while steps_done < steps:
current_index = steps_done * batch_size
until_index = current_index + batch_size
x_test = np.asarray(out[current_index:until_index])
decode, log = K.ctc_decode(x_test,
x_test_len,
greedy=self.greedy,
beam_width=self.beam_width,
top_paths=self.top_paths)
probabilities.extend([np.exp(x) for x in log])
decode = [[[int(p) for p in x if p != -1] for x in y]
for y in decode]
predicts.extend(np.swapaxes(decode, 0, 1))
steps_done += 1
if verbose == 1:
progbar.update(steps_done)
return (predicts, probabilities)
@staticmethod
def ctc_loss_lambda_func(args):
"""
Function for computing the ctc loss (can be put in a Lambda layer)
:param args:
y_pred, labels, input_length, label_length
:return: CTC loss
"""
y_pred, labels, input_length, label_length = args
return K.ctc_batch_cost(labels, y_pred, input_length, label_length)