/
models.py
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models.py
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from ..imports import *
from .. import utils as U
from .wrn import create_wide_residual_network
PRETRAINED_RESNET50 = 'pretrained_resnet50'
PRETRAINED_MOBILENET = 'pretrained_mobilenet'
PRETRAINED_INCEPTION = 'pretrained_inception'
RESNET50 = 'resnet50'
MOBILENET = 'mobilenet'
INCEPTION = 'inception'
CNN = 'default_cnn'
WRN22 = 'wrn22'
PRETRAINED_MODELS = [PRETRAINED_RESNET50, PRETRAINED_MOBILENET, PRETRAINED_INCEPTION]
PREDEFINED_MODELS = PRETRAINED_MODELS + [RESNET50, MOBILENET, INCEPTION]
IMAGE_CLASSIFIERS = {
PRETRAINED_RESNET50: '50-layer Residual Network (pretrained on ImageNet)',
RESNET50: '50-layer Resididual Network (randomly initialized)',
PRETRAINED_MOBILENET: 'MobileNet Neural Network (pretrained on ImageNet)',
MOBILENET: 'MobileNet Neural Network (randomly initialized)',
PRETRAINED_INCEPTION: 'Inception Version 3 (pretrained on ImageNet)',
INCEPTION: 'Inception Version 3 (randomly initialized)',
WRN22: '22-layer Wide Residual Network (randomly initialized)',
CNN : 'a default LeNet-like Convolutional Neural Network'}
def print_image_classifiers():
for k,v in IMAGE_CLASSIFIERS.items():
print("%s: %s" % (k,v))
def print_image_regression_models():
for k,v in IMAGE_CLASSIFIERS.items():
print("%s: %s" % (k,v))
def pretrained_datagen(data, name):
if not data or not U.is_iter(data): return
idg = data.image_data_generator
if name == PRETRAINED_RESNET50:
idg.preprocessing_function = pre_resnet50
idg.ktrain_preproc = 'resnet50'
idg.rescale=None
idg.featurewise_center=False
idg.samplewise_center=False
idg.featurewise_std_normalization=False
idg.samplewise_std_normalization=False
idg.zca_whitening = False
elif name == PRETRAINED_MOBILENET:
idg.preprocessing_function = pre_mobilenet
idg.ktrain_preproc = 'mobilenet'
idg.rescale=None
idg.featurewise_center=False
idg.samplewise_center=False
idg.featurewise_std_normalization=False
idg.samplewise_std_normalization=False
idg.zca_whitening = False
elif name == PRETRAINED_INCEPTION:
idg.preprocessing_function = pre_inception
idg.ktrain_preproc = 'inception'
idg.rescale=None
idg.featurewise_center=False
idg.samplewise_center=False
idg.featurewise_std_normalization=False
idg.samplewise_std_normalization=False
idg.zca_whitening = False
return
def image_classifier(name,
train_data,
val_data=None,
freeze_layers=None,
metrics=['accuracy'],
optimizer_name = U.DEFAULT_OPT,
multilabel=None,
pt_fc = [],
pt_ps = [],
verbose=1):
"""
```
Returns a pre-trained ResNet50 model ready to be fine-tuned
for multi-class classification. By default, all layers are
trainable/unfrozen.
Args:
name (string): one of {'pretrained_resnet50', 'resnet50', 'default_cnn'}
train_data (image.Iterator): train data. Note: Will be manipulated here!
val_data (image.Iterator): validation data. Note: Will be manipulated here!
freeze_layers (int): number of beginning layers to make untrainable
If None, then all layers except new Dense layers
will be frozen/untrainable.
metrics (list): metrics to use
optimizer_name(str): name of Keras optimizer (e.g., 'adam', 'sgd')
multilabel(bool): If True, model will be build to support
multilabel classificaiton (labels are not mutually exclusive).
If False, binary/multiclassification model will be returned.
If None, multilabel status will be inferred from data.
pt_fc (list of ints): number of hidden units in extra Dense layers
before final Dense layer of pretrained model.
Only takes effect if name in PRETRAINED_MODELS
pt_ps (list of floats): dropout probabilities to use before
each extra Dense layer in pretrained model.
Only takes effect if name in PRETRAINED_MODELS
verbose (int): verbosity
Return:
model(Model): the compiled model ready to be fine-tuned/trained
```
"""
return image_model(name, train_data, val_data=val_data, freeze_layers=freeze_layers,
metrics=metrics, optimizer_name=optimizer_name, multilabel=multilabel,
pt_fc=pt_fc, pt_ps=pt_ps, verbose=verbose)
def image_regression_model(name,
train_data,
val_data=None,
freeze_layers=None,
metrics=['mae'],
optimizer_name = U.DEFAULT_OPT,
pt_fc = [],
pt_ps = [],
verbose=1):
"""
```
Returns a pre-trained ResNet50 model ready to be fine-tuned
for multi-class classification. By default, all layers are
trainable/unfrozen.
Args:
name (string): one of {'pretrained_resnet50', 'resnet50', 'default_cnn'}
train_data (image.Iterator): train data. Note: Will be manipulated here!
val_data (image.Iterator): validation data. Note: Will be manipulated here!
freeze_layers (int): number of beginning layers to make untrainable
If None, then all layers except new Dense layers
will be frozen/untrainable.
metrics (list): metrics to use
optimizer_name(str): name of Keras optimizer (e.g., 'adam', 'sgd')
multilabel(bool): If True, model will be build to support
multilabel classificaiton (labels are not mutually exclusive).
If False, binary/multiclassification model will be returned.
If None, multilabel status will be inferred from data.
pt_fc (list of ints): number of hidden units in extra Dense layers
before final Dense layer of pretrained model.
Only takes effect if name in PRETRAINED_MODELS
pt_ps (list of floats): dropout probabilities to use before
each extra Dense layer in pretrained model.
Only takes effect if name in PRETRAINED_MODELS
verbose (int): verbosity
Return:
model(Model): the compiled model ready to be fine-tuned/trained
```
"""
return image_model(name, train_data, val_data=val_data, freeze_layers=freeze_layers,
metrics=metrics, optimizer_name=optimizer_name, multilabel=False,
pt_fc=pt_fc, pt_ps=pt_ps, verbose=verbose)
def image_model( name,
train_data,
val_data=None,
freeze_layers=None,
metrics=['accuracy'],
optimizer_name = U.DEFAULT_OPT,
multilabel=None,
pt_fc = [],
pt_ps = [],
verbose=1):
"""
```
Returns a pre-trained ResNet50 model ready to be fine-tuned
for multi-class classification or regression. By default, all layers are
trainable/unfrozen.
Args:
name (string): one of {'pretrained_resnet50', 'resnet50', 'default_cnn'}
train_data (image.Iterator): train data. Note: Will be manipulated here!
val_data (image.Iterator): validation data. Note: Will be manipulated here!
freeze_layers (int): number of beginning layers to make untrainable
If None, then all layers except new Dense layers
will be frozen/untrainable.
metrics (list): metrics to use
optimizer_name(str): name of Keras optimizer (e.g., 'adam', 'sgd')
multilabel(bool): If True, model will be build to support
multilabel classificaiton (labels are not mutually exclusive).
If False, binary/multiclassification model will be returned.
If None, multilabel status will be inferred from data.
pt_fc (list of ints): number of hidden units in extra Dense layers
before final Dense layer of pretrained model.
Only takes effect if name in PRETRAINED_MODELS
pt_ps (list of floats): dropout probabilities to use before
each extra Dense layer in pretrained model.
Only takes effect if name in PRETRAINED_MODELS
verbose (int): verbosity
Return:
model(Model): the compiled model ready to be fine-tuned/trained
```
"""
# arg check
U.data_arg_check(train_data=train_data, train_required=True)
if name not in list(IMAGE_CLASSIFIERS.keys()):
raise ValueError('Unknown or unsupported model: %s' % (name))
if not U.is_iter(train_data):
raise ValueError('train_data must be an Keras iterator ' +\
'(e.g., DirectoryIterator, DataframIterator, '+ \
'NumpyArrayIterator) - please use the ktrain.data.images_from* ' +\
'functions')
# set pretrained flag
pretrained = True if name in PRETRAINED_MODELS else False
# adjust freeze_layers with warning
if not pretrained and freeze_layers is not None and freeze_layers > 0:
warnings.warn('Only pretrained models (e.g., pretrained_resnet50) support freeze_layers. ' +\
'Setting freeze_layers to 0. Use one of the following models if' +\
'desiring a model pretrained on ImageNet: %s' % (PRETRAINED_MODELS))
freeze_layers = 0
if pretrained and val_data is None:
raise ValueError('val_data is required if selecting a pretrained model, '+\
'as normalization scheme will be altered.')
# adjust the data augmentation based on model selected
if pretrained:
pretrained_datagen(train_data, name)
pretrained_datagen(val_data, name)
U.vprint('The normalization scheme has been changed for use with a %s' % (name) +\
' model. If you decide to use a different model, please reload your' +\
' dataset with a ktrain.vision.data.images_from* function.\n', verbose=verbose)
# determine if multilabel
if multilabel is None:
multilabel = U.is_multilabel(train_data)
is_regression=False
if not multilabel and len(train_data[0][-1].shape) == 1: is_regression=True
# set loss and acivations
loss_func = 'categorical_crossentropy'
activation = 'softmax'
if multilabel:
loss_func = 'binary_crossentropy'
activation = 'sigmoid'
elif is_regression:
loss_func = 'mse'
activation = None
if metrics == ['accuracy']: metrics = ['mae']
U.vprint("Is Multi-Label? %s" % (multilabel), verbose=verbose)
U.vprint("Is Regression? %s" % (is_regression), verbose=verbose)
# determine number of classes and shape
num_classes = 1 if is_regression else U.nclasses_from_data(train_data)
input_shape = U.shape_from_data(train_data)
#------------
# build model
#------------
model = build_visionmodel(name,
num_classes,
input_shape=input_shape,
freeze_layers=freeze_layers,
activation=activation,
pt_fc = pt_fc,
pt_ps = pt_ps)
model.compile(optimizer=optimizer_name, loss=loss_func, metrics=metrics)
return model
def build_visionmodel(name,
num_classes,
input_shape=(224,224,3),
freeze_layers=2,
activation='softmax',
pt_fc=[],
pt_ps = []):
if name in PREDEFINED_MODELS:
model = build_predefined(name, num_classes,
input_shape=input_shape,
freeze_layers=freeze_layers,
activation=activation,
pt_fc = pt_fc,
pt_ps = pt_ps)
elif name == CNN:
model = build_cnn(num_classes,
input_shape=input_shape,
activation=activation)
elif name == WRN22:
model = create_wide_residual_network(input_shape, nb_classes=num_classes,
N=3, k=6, dropout=0.00,
activation=activation, verbose=0)
else:
raise ValueError('Unknown model: %s' % (name))
U.vprint('%s model created.' % (name))
return model
def build_cnn(num_classes,
input_shape=(28,28,1),
activation='softmax'):
model = Sequential()
model.add(Conv2D(32, kernel_size=(3, 3),activation='relu',
kernel_initializer='he_normal',input_shape=input_shape))
model.add(Conv2D(32, kernel_size=(3, 3),activation='relu',
kernel_initializer='he_normal'))
model.add(MaxPooling2D((2, 2)))
model.add(Dropout(0.20))
model.add(Conv2D(64, (3, 3), activation='relu',padding='same',
kernel_initializer='he_normal'))
model.add(Conv2D(64, (3, 3), activation='relu',padding='same',
kernel_initializer='he_normal'))
model.add(MaxPooling2D(pool_size=(2, 2)))
model.add(Dropout(0.25))
model.add(Conv2D(128, (3, 3), activation='relu',padding='same',
kernel_initializer='he_normal'))
model.add(Dropout(0.25))
model.add(Flatten())
model.add(Dense(128, activation='relu'))
model.add(BatchNormalization())
model.add(Dropout(0.25))
model.add(Dense(num_classes, activation=activation))
return model
def build_predefined(
name,
num_classes,
input_shape=(224,224,3),
freeze_layers=None,
activation='softmax',
pt_fc=[],
pt_ps=[]):
"""
```
Builds a pre-defined architecture supported in Keras.
Args:
name (str): one of ktrain.vision.model.PREDEFINED_MODELS
num_classes (int): # of classes
input_shape (tuple): the input shape including channels
freeze_layers (int): number of early layers to freeze.
Only takes effect if name in PRETRAINED_MODELS.
If None and name in PRETRAINED_MODELS,
all layers except the "custom head"
fully-connected (Dense) layers are frozen.
activation (str): name of the Keras activation to use in final layer
pt_fc (list of ints): number of hidden units in extra Dense layers
before final Dense layer of pretrained model
pt_ps (list of floats): dropout probabilities to use before
each extra Dense layer in pretrained model
```
"""
# default parameters
include_top = False
input_tensor = None
dropout = 0.5 # final dropout
# setup pretrained
weights = 'imagenet' if name in PRETRAINED_MODELS else None
# setup the pretrained network
if name in [RESNET50, PRETRAINED_RESNET50]:
with warnings.catch_warnings():
warnings.simplefilter('ignore')
net = ResNet50(include_top=include_top,
weights=weights,
input_tensor=input_tensor,
input_shape = input_shape)
elif name in [MOBILENET, PRETRAINED_MOBILENET]:
net = MobileNet(include_top=include_top,
weights=weights,
input_tensor=input_tensor,
input_shape = input_shape)
elif name in [INCEPTION, PRETRAINED_INCEPTION]:
net = InceptionV3(include_top=include_top,
weights=weights,
input_tensor=input_tensor,
input_shape = input_shape)
else:
raise ValueError('Unsupported model: %s' % (name))
if freeze_layers is None:
for layer in net.layers:
layer.trainable = False
x = net.output
x = Flatten()(x)
# xtra FCs in pretrained model
if name in PRETRAINED_MODELS:
if len(pt_fc) != len(pt_ps):
raise ValueError('size off xtra_fc must match size of fc_dropouts')
for i, fc in enumerate(pt_fc):
p = pt_ps[i]
fc_name = "fc%s" % (i)
if p is not None:
x = Dropout(p)(x)
x = Dense(fc, activation='relu',
kernel_initializer='he_normal', name=fc_name)(x)
# final FC
x = Dropout(dropout)(x)
output_layer = Dense(num_classes, activation=activation, name=activation)(x)
model = Model(inputs=net.input, outputs=output_layer)
if freeze_layers is not None:
# set certain earlier layers as non-trainable
for layer in model.layers[:freeze_layers]:
layer.trainable = False
for layer in model.layers[freeze_layers:]:
layer.trainable = True
# set optimizer, loss, and metrics and return model
return model