Chapter 43
Modern convnet architecture patterns
NotebookPython 318 cells
This is a companion notebook for the book Deep Learning with Python, Second Edition. For readability, it only contains runnable code blocks and section titles, and omits everything else in the book: text paragraphs, figures, and pseudocode.
If you want to be able to follow what's going on, I recommend reading the notebook side by side with your copy of the book.
This notebook was generated for TensorFlow 2.6.
Modern convnet architecture patterns
Modularity, hierarchy, and reuse
Residual connections
Residual block where the number of filters changes
In [0]python · cell 6
python
from tensorflow import keras
from tensorflow.keras import layers
inputs = keras.Input(shape=(32, 32, 3))
x = layers.Conv2D(32, 3, activation="relu")(inputs)
residual = x
x = layers.Conv2D(64, 3, activation="relu", padding="same")(x)
residual = layers.Conv2D(64, 1)(residual)
x = layers.add([x, residual])Case where target block includes a max pooling layer
In [0]python · cell 8
python
inputs = keras.Input(shape=(32, 32, 3))
x = layers.Conv2D(32, 3, activation="relu")(inputs)
residual = x
x = layers.Conv2D(64, 3, activation="relu", padding="same")(x)
x = layers.MaxPooling2D(2, padding="same")(x)
residual = layers.Conv2D(64, 1, strides=2)(residual)
x = layers.add([x, residual])In [0]python · cell 9
python
inputs = keras.Input(shape=(32, 32, 3))
x = layers.Rescaling(1./255)(inputs)
def residual_block(x, filters, pooling=False):
residual = x
x = layers.Conv2D(filters, 3, activation="relu", padding="same")(x)
x = layers.Conv2D(filters, 3, activation="relu", padding="same")(x)
if pooling:
x = layers.MaxPooling2D(2, padding="same")(x)
residual = layers.Conv2D(filters, 1, strides=2)(residual)
elif filters != residual.shape[-1]:
residual = layers.Conv2D(filters, 1)(residual)
x = layers.add([x, residual])
return x
x = residual_block(x, filters=32, pooling=True)
x = residual_block(x, filters=64, pooling=True)
x = residual_block(x, filters=128, pooling=False)
x = layers.GlobalAveragePooling2D()(x)
outputs = layers.Dense(1, activation="sigmoid")(x)
model = keras.Model(inputs=inputs, outputs=outputs)
model.summary()Batch normalization
Depthwise separable convolutions
Putting it together: A mini Xception-like model
In [0]python · cell 13
python
from google.colab import files
files.upload()In [0]python · cell 14
python
!mkdir ~/.kaggle
!cp kaggle.json ~/.kaggle/
!chmod 600 ~/.kaggle/kaggle.json
!kaggle competitions download -c dogs-vs-cats
!unzip -qq train.zipIn [0]python · cell 15
python
import os, shutil, pathlib
from tensorflow.keras.utils import image_dataset_from_directory
original_dir = pathlib.Path("train")
new_base_dir = pathlib.Path("cats_vs_dogs_small")
def make_subset(subset_name, start_index, end_index):
for category in ("cat", "dog"):
dir = new_base_dir / subset_name / category
os.makedirs(dir)
fnames = [f"{category}.{i}.jpg" for i in range(start_index, end_index)]
for fname in fnames:
shutil.copyfile(src=original_dir / fname,
dst=dir / fname)
make_subset("train", start_index=0, end_index=1000)
make_subset("validation", start_index=1000, end_index=1500)
make_subset("test", start_index=1500, end_index=2500)
train_dataset = image_dataset_from_directory(
new_base_dir / "train",
image_size=(180, 180),
batch_size=32)
validation_dataset = image_dataset_from_directory(
new_base_dir / "validation",
image_size=(180, 180),
batch_size=32)
test_dataset = image_dataset_from_directory(
new_base_dir / "test",
image_size=(180, 180),
batch_size=32)In [0]python · cell 16
python
data_augmentation = keras.Sequential(
[
layers.RandomFlip("horizontal"),
layers.RandomRotation(0.1),
layers.RandomZoom(0.2),
]
)In [0]python · cell 17
python
inputs = keras.Input(shape=(180, 180, 3))
x = data_augmentation(inputs)
x = layers.Rescaling(1./255)(x)
x = layers.Conv2D(filters=32, kernel_size=5, use_bias=False)(x)
for size in [32, 64, 128, 256, 512]:
residual = x
x = layers.BatchNormalization()(x)
x = layers.Activation("relu")(x)
x = layers.SeparableConv2D(size, 3, padding="same", use_bias=False)(x)
x = layers.BatchNormalization()(x)
x = layers.Activation("relu")(x)
x = layers.SeparableConv2D(size, 3, padding="same", use_bias=False)(x)
x = layers.MaxPooling2D(3, strides=2, padding="same")(x)
residual = layers.Conv2D(
size, 1, strides=2, padding="same", use_bias=False)(residual)
x = layers.add([x, residual])
x = layers.GlobalAveragePooling2D()(x)
x = layers.Dropout(0.5)(x)
outputs = layers.Dense(1, activation="sigmoid")(x)
model = keras.Model(inputs=inputs, outputs=outputs)In [0]python · cell 18
python
model.compile(loss="binary_crossentropy",
optimizer="rmsprop",
metrics=["accuracy"])
history = model.fit(
train_dataset,
epochs=100,
validation_data=validation_dataset)