Keras 调试技巧

import os

# The last example uses tf.GradientTape and thus requires TensorFlow.
# However, all tips here are applicable with all backends.
os.environ["KERAS_BACKEND"] = "tensorflow"

import keras
from keras import layers
from keras import ops
import numpy as np
import tensorflow as tf


class MyAntirectifier(layers.Layer):
    def build(self, input_shape):
        output_dim = input_shape[-1]
        self.kernel = self.add_weight(
            shape=(output_dim * 2, output_dim),
            initializer="he_normal",
            name="kernel",
            trainable=True,
        )

    def call(self, inputs):
        # Take the positive part of the input
        pos = ops.relu(inputs)
        # Take the negative part of the input
        neg = ops.relu(-inputs)
        # Concatenate the positive and negative parts
        concatenated = ops.concatenate([pos, neg], axis=0)
        # Project the concatenation down to the same dimensionality as the input
        return ops.matmul(concatenated, self.kernel)

x = tf.random.normal(shape=(2, 5))
y = MyAntirectifier()(x)

...
      1 x = tf.random.normal(shape=(2, 5))
----> 2 y = MyAntirectifier()(x)
...
     17         neg = tf.nn.relu(-inputs)
     18         concatenated = tf.concat([pos, neg], axis=0)
---> 19         return tf.matmul(concatenated, self.kernel)
...
InvalidArgumentError: Matrix size-incompatible: In[0]: [4,5], In[1]: [10,5] [Op:MatMul]

class MyAntirectifier(layers.Layer):
    def build(self, input_shape):
        output_dim = input_shape[-1]
        self.kernel = self.add_weight(
            shape=(output_dim * 2, output_dim),
            initializer="he_normal",
            name="kernel",
            trainable=True,
        )

    def call(self, inputs):
        pos = ops.relu(inputs)
        neg = ops.relu(-inputs)
        print("pos.shape:", pos.shape)
        print("neg.shape:", neg.shape)
        concatenated = ops.concatenate([pos, neg], axis=0)
        print("concatenated.shape:", concatenated.shape)
        print("kernel.shape:", self.kernel.shape)
        return ops.matmul(concatenated, self.kernel)

pos.shape: (2, 5)
neg.shape: (2, 5)
concatenated.shape: (4, 5)
kernel.shape: (10, 5)

class MyAntirectifier(layers.Layer):
    def build(self, input_shape):
        output_dim = input_shape[-1]
        self.kernel = self.add_weight(
            shape=(output_dim * 2, output_dim),
            initializer="he_normal",
            name="kernel",
            trainable=True,
        )

    def call(self, inputs):
        pos = ops.relu(inputs)
        neg = ops.relu(-inputs)
        print("pos.shape:", pos.shape)
        print("neg.shape:", neg.shape)
        concatenated = ops.concatenate([pos, neg], axis=1)
        print("concatenated.shape:", concatenated.shape)
        print("kernel.shape:", self.kernel.shape)
        return ops.matmul(concatenated, self.kernel)

x = keras.random.normal(shape=(2, 5))
y = MyAntirectifier()(x)

num_tags = 12  # Number of unique issue tags
num_words = 10000  # Size of vocabulary obtained when preprocessing text data
num_departments = 4  # Number of departments for predictions

title_input = keras.Input(
    shape=(None,), name="title"
)  # Variable-length sequence of ints
body_input = keras.Input(shape=(None,), name="body")  # Variable-length sequence of ints
tags_input = keras.Input(
    shape=(num_tags,), name="tags"
)  # Binary vectors of size `num_tags`

# Embed each word in the title into a 64-dimensional vector
title_features = layers.Embedding(num_words, 64)(title_input)
# Embed each word in the text into a 64-dimensional vector
body_features = layers.Embedding(num_words, 64)(body_input)

# Reduce sequence of embedded words in the title into a single 128-dimensional vector
title_features = layers.LSTM(128)(title_features)
# Reduce sequence of embedded words in the body into a single 32-dimensional vector
body_features = layers.LSTM(32)(body_features)

# Merge all available features into a single large vector via concatenation
x = layers.concatenate([title_features, body_features, tags_input])

# Stick a logistic regression for priority prediction on top of the features
priority_pred = layers.Dense(1, name="priority")(x)
# Stick a department classifier on top of the features
department_pred = layers.Dense(num_departments, name="department")(x)

# Instantiate an end-to-end model predicting both priority and department
model = keras.Model(
    inputs=[title_input, body_input, tags_input],
    outputs=[priority_pred, department_pred],
)

model.summary()

keras.utils.plot_model(model, show_shapes=True)

class MyModel(keras.Model):
    def train_step(self, data):
        inputs, targets = data
        trainable_vars = self.trainable_variables
        with tf.GradientTape() as tape2:
            with tf.GradientTape() as tape1:
                y_pred = self(inputs, training=True)  # Forward pass
                # Compute the loss value
                # (the loss function is configured in `compile()`)
                loss = self.compute_loss(y=targets, y_pred=y_pred)
            # Compute first-order gradients
            dl_dw = tape1.gradient(loss, trainable_vars)
        # Compute second-order gradients
        d2l_dw2 = tape2.gradient(dl_dw, trainable_vars)

        # Combine first-order and second-order gradients
        grads = [0.5 * w1 + 0.5 * w2 for (w1, w2) in zip(d2l_dw2, dl_dw)]

        # Update weights
        self.optimizer.apply_gradients(zip(grads, trainable_vars))

        # Update metrics (includes the metric that tracks the loss)
        for metric in self.metrics:
            if metric.name == "loss":
                metric.update_state(loss)
            else:
                metric.update_state(targets, y_pred)

        # Return a dict mapping metric names to current value
        return {m.name: m.result() for m in self.metrics}

# Construct an instance of MyModel
def get_model():
    inputs = keras.Input(shape=(784,))
    intermediate = layers.Dense(256, activation="relu")(inputs)
    outputs = layers.Dense(10, activation="softmax")(intermediate)
    model = MyModel(inputs, outputs)
    return model


# Prepare data
(x_train, y_train), _ = keras.datasets.mnist.load_data()
x_train = np.reshape(x_train, (-1, 784)) / 255

model = get_model()
model.compile(
    optimizer=keras.optimizers.SGD(learning_rate=1e-2),
    loss="sparse_categorical_crossentropy",
)
model.fit(x_train, y_train, epochs=3, batch_size=1024, validation_split=0.1)

class MyModel(keras.Model):
    def train_step(self, data):
        print()
        print("----Start of step: %d" % (self.step_counter,))
        self.step_counter += 1

        inputs, targets = data
        trainable_vars = self.trainable_variables
        with tf.GradientTape() as tape2:
            with tf.GradientTape() as tape1:
                y_pred = self(inputs, training=True)  # Forward pass
                # Compute the loss value
                # (the loss function is configured in `compile()`)
                loss = self.compute_loss(y=targets, y_pred=y_pred)
            # Compute first-order gradients
            dl_dw = tape1.gradient(loss, trainable_vars)
        # Compute second-order gradients
        d2l_dw2 = tape2.gradient(dl_dw, trainable_vars)

        print("Max of dl_dw[0]: %.4f" % tf.reduce_max(dl_dw[0]))
        print("Min of dl_dw[0]: %.4f" % tf.reduce_min(dl_dw[0]))
        print("Mean of dl_dw[0]: %.4f" % tf.reduce_mean(dl_dw[0]))
        print("-")
        print("Max of d2l_dw2[0]: %.4f" % tf.reduce_max(d2l_dw2[0]))
        print("Min of d2l_dw2[0]: %.4f" % tf.reduce_min(d2l_dw2[0]))
        print("Mean of d2l_dw2[0]: %.4f" % tf.reduce_mean(d2l_dw2[0]))

        # Combine first-order and second-order gradients
        grads = [0.5 * w1 + 0.5 * w2 for (w1, w2) in zip(d2l_dw2, dl_dw)]

        # Update weights
        self.optimizer.apply_gradients(zip(grads, trainable_vars))

        # Update metrics (includes the metric that tracks the loss)
        for metric in self.metrics:
            if metric.name == "loss":
                metric.update_state(loss)
            else:
                metric.update_state(targets, y_pred)

        # Return a dict mapping metric names to current value
        return {m.name: m.result() for m in self.metrics}


model = get_model()
model.compile(
    optimizer=keras.optimizers.SGD(learning_rate=1e-2),
    loss="sparse_categorical_crossentropy",
    metrics=["sparse_categorical_accuracy"],
    run_eagerly=True,
)
model.step_counter = 0
# We pass epochs=1 and steps_per_epoch=10 to only run 10 steps of training.
model.fit(x_train, y_train, epochs=1, batch_size=1024, verbose=0, steps_per_epoch=10)

class MyModel(keras.Model):
    def train_step(self, data):
        inputs, targets = data
        trainable_vars = self.trainable_variables
        with tf.GradientTape() as tape2:
            with tf.GradientTape() as tape1:
                y_pred = self(inputs, training=True)  # Forward pass
                # Compute the loss value
                # (the loss function is configured in `compile()`)
                loss = self.compute_loss(y=targets, y_pred=y_pred)
            # Compute first-order gradients
            dl_dw = tape1.gradient(loss, trainable_vars)
        # Compute second-order gradients
        d2l_dw2 = tape2.gradient(dl_dw, trainable_vars)

        dl_dw = [tf.math.l2_normalize(w) for w in dl_dw]
        d2l_dw2 = [tf.math.l2_normalize(w) for w in d2l_dw2]

        # Combine first-order and second-order gradients
        grads = [0.5 * w1 + 0.5 * w2 for (w1, w2) in zip(d2l_dw2, dl_dw)]

        # Update weights
        self.optimizer.apply_gradients(zip(grads, trainable_vars))

        # Update metrics (includes the metric that tracks the loss)
        for metric in self.metrics:
            if metric.name == "loss":
                metric.update_state(loss)
            else:
                metric.update_state(targets, y_pred)

        # Return a dict mapping metric names to current value
        return {m.name: m.result() for m in self.metrics}


model = get_model()
model.compile(
    optimizer=keras.optimizers.SGD(learning_rate=1e-2),
    loss="sparse_categorical_crossentropy",
    metrics=["sparse_categorical_accuracy"],
)
model.fit(x_train, y_train, epochs=5, batch_size=1024, validation_split=0.1)

class MyModel(keras.Model):
    def train_step(self, data):
        inputs, targets = data
        trainable_vars = self.trainable_variables
        with tf.GradientTape() as tape2:
            with tf.GradientTape() as tape1:
                y_pred = self(inputs, training=True)  # Forward pass
                # Compute the loss value
                # (the loss function is configured in `compile()`)
                loss = self.compute_loss(y=targets, y_pred=y_pred)
            # Compute first-order gradients
            dl_dw = tape1.gradient(loss, trainable_vars)
        # Compute second-order gradients
        d2l_dw2 = tape2.gradient(dl_dw, trainable_vars)

        dl_dw = [tf.math.l2_normalize(w) for w in dl_dw]
        d2l_dw2 = [tf.math.l2_normalize(w) for w in d2l_dw2]

        # Combine first-order and second-order gradients
        grads = [0.2 * w1 + 0.8 * w2 for (w1, w2) in zip(d2l_dw2, dl_dw)]

        # Update weights
        self.optimizer.apply_gradients(zip(grads, trainable_vars))

        # Update metrics (includes the metric that tracks the loss)
        for metric in self.metrics:
            if metric.name == "loss":
                metric.update_state(loss)
            else:
                metric.update_state(targets, y_pred)

        # Return a dict mapping metric names to current value
        return {m.name: m.result() for m in self.metrics}


model = get_model()
lr = learning_rate = keras.optimizers.schedules.InverseTimeDecay(
    initial_learning_rate=0.1, decay_steps=25, decay_rate=0.1
)
model.compile(
    optimizer=keras.optimizers.SGD(lr),
    loss="sparse_categorical_crossentropy",
    metrics=["sparse_categorical_accuracy"],
)
model.fit(x_train, y_train, epochs=50, batch_size=2048, validation_split=0.1)