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Prediction mean: 6.39, stddev: 0.78, 95% CI: [7.92 - 4.85] - Actual: 7.0 |
Demonstration of custom layer creation. |
Introduction |
This example shows how to create custom layers, using the Antirectifier layer (originally proposed as a Keras example script in January 2016), an alternative to ReLU. Instead of zeroing-out the negative part of the input, it splits the negative and positive parts and returns the concatenation of the absolute value of b... |
Setup |
import tensorflow as tf |
from tensorflow import keras |
from tensorflow.keras import layers |
The Antirectifier layer |
class Antirectifier(layers.Layer): |
def __init__(self, initializer=\"he_normal\", **kwargs): |
super(Antirectifier, self).__init__(**kwargs) |
self.initializer = keras.initializers.get(initializer) |
def build(self, input_shape): |
output_dim = input_shape[-1] |
self.kernel = self.add_weight( |
shape=(output_dim * 2, output_dim), |
initializer=self.initializer, |
name=\"kernel\", |
trainable=True, |
) |
def call(self, inputs): |
inputs -= tf.reduce_mean(inputs, axis=-1, keepdims=True) |
pos = tf.nn.relu(inputs) |
neg = tf.nn.relu(-inputs) |
concatenated = tf.concat([pos, neg], axis=-1) |
mixed = tf.matmul(concatenated, self.kernel) |
return mixed |
def get_config(self): |
# Implement get_config to enable serialization. This is optional. |
base_config = super(Antirectifier, self).get_config() |
config = {\"initializer\": keras.initializers.serialize(self.initializer)} |
return dict(list(base_config.items()) + list(config.items())) |
Let's test-drive it on MNIST |
# Training parameters |
batch_size = 128 |
num_classes = 10 |
epochs = 20 |
# The data, split between train and test sets |
(x_train, y_train), (x_test, y_test) = keras.datasets.mnist.load_data() |
x_train = x_train.reshape(-1, 784) |
x_test = x_test.reshape(-1, 784) |
x_train = x_train.astype(\"float32\") |
x_test = x_test.astype(\"float32\") |
x_train /= 255 |
x_test /= 255 |
print(x_train.shape[0], \"train samples\") |
print(x_test.shape[0], \"test samples\") |
# Build the model |
model = keras.Sequential( |
[ |
keras.Input(shape=(784,)), |
layers.Dense(256), |
Antirectifier(), |
layers.Dense(256), |
Antirectifier(), |
layers.Dropout(0.5), |
layers.Dense(10), |
] |
) |
# Compile the model |
model.compile( |
loss=keras.losses.SparseCategoricalCrossentropy(from_logits=True), |
optimizer=keras.optimizers.RMSprop(), |
metrics=[keras.metrics.SparseCategoricalAccuracy()], |
) |
# Train the model |
model.fit(x_train, y_train, batch_size=batch_size, epochs=epochs, validation_split=0.15) |
# Test the model |
model.evaluate(x_test, y_test) |
60000 train samples |
10000 test samples |
Epoch 1/20 |
399/399 [==============================] - 2s 5ms/step - loss: 0.3827 - sparse_categorical_accuracy: 0.8882 - val_loss: 0.1407 - val_sparse_categorical_accuracy: 0.9587 |
Epoch 2/20 |
399/399 [==============================] - 2s 5ms/step - loss: 0.1771 - sparse_categorical_accuracy: 0.9513 - val_loss: 0.1337 - val_sparse_categorical_accuracy: 0.9674 |
Epoch 3/20 |
399/399 [==============================] - 2s 5ms/step - loss: 0.1400 - sparse_categorical_accuracy: 0.9620 - val_loss: 0.1225 - val_sparse_categorical_accuracy: 0.9709 |
Epoch 4/20 |
399/399 [==============================] - 2s 5ms/step - loss: 0.1099 - sparse_categorical_accuracy: 0.9707 - val_loss: 0.1465 - val_sparse_categorical_accuracy: 0.9636 |
Epoch 5/20 |
399/399 [==============================] - 2s 5ms/step - loss: 0.0996 - sparse_categorical_accuracy: 0.9739 - val_loss: 0.1703 - val_sparse_categorical_accuracy: 0.9626 |
Epoch 6/20 |
399/399 [==============================] - 2s 5ms/step - loss: 0.0860 - sparse_categorical_accuracy: 0.9774 - val_loss: 0.1354 - val_sparse_categorical_accuracy: 0.9712 |
Epoch 7/20 |
399/399 [==============================] - 2s 5ms/step - loss: 0.0833 - sparse_categorical_accuracy: 0.9791 - val_loss: 0.2018 - val_sparse_categorical_accuracy: 0.9574 |
Epoch 8/20 |
399/399 [==============================] - 2s 5ms/step - loss: 0.0712 - sparse_categorical_accuracy: 0.9814 - val_loss: 0.1527 - val_sparse_categorical_accuracy: 0.9723 |
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