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self.dropout_1 = layers.Dropout(0.3) |
self.dropout_2 = layers.Dropout(0.5) |
self.supports_masking = True |
def call(self, inputs, encoder_outputs, training, mask=None): |
inputs = self.embedding(inputs) |
causal_mask = self.get_causal_attention_mask(inputs) |
if mask is not None: |
padding_mask = tf.cast(mask[:, :, tf.newaxis], dtype=tf.int32) |
combined_mask = tf.cast(mask[:, tf.newaxis, :], dtype=tf.int32) |
combined_mask = tf.minimum(combined_mask, causal_mask) |
attention_output_1 = self.attention_1( |
query=inputs, |
value=inputs, |
key=inputs, |
attention_mask=combined_mask, |
training=training, |
) |
out_1 = self.layernorm_1(inputs + attention_output_1) |
attention_output_2 = self.attention_2( |
query=out_1, |
value=encoder_outputs, |
key=encoder_outputs, |
attention_mask=padding_mask, |
training=training, |
) |
out_2 = self.layernorm_2(out_1 + attention_output_2) |
ffn_out = self.ffn_layer_1(out_2) |
ffn_out = self.dropout_1(ffn_out, training=training) |
ffn_out = self.ffn_layer_2(ffn_out) |
ffn_out = self.layernorm_3(ffn_out + out_2, training=training) |
ffn_out = self.dropout_2(ffn_out, training=training) |
preds = self.out(ffn_out) |
return preds |
def get_causal_attention_mask(self, inputs): |
input_shape = tf.shape(inputs) |
batch_size, sequence_length = input_shape[0], input_shape[1] |
i = tf.range(sequence_length)[:, tf.newaxis] |
j = tf.range(sequence_length) |
mask = tf.cast(i >= j, dtype=\"int32\") |
mask = tf.reshape(mask, (1, input_shape[1], input_shape[1])) |
mult = tf.concat( |
[tf.expand_dims(batch_size, -1), tf.constant([1, 1], dtype=tf.int32)], |
axis=0, |
) |
return tf.tile(mask, mult) |
class ImageCaptioningModel(keras.Model): |
def __init__( |
self, cnn_model, encoder, decoder, num_captions_per_image=5, image_aug=None, |
): |
super().__init__() |
self.cnn_model = cnn_model |
self.encoder = encoder |
self.decoder = decoder |
self.loss_tracker = keras.metrics.Mean(name=\"loss\") |
self.acc_tracker = keras.metrics.Mean(name=\"accuracy\") |
self.num_captions_per_image = num_captions_per_image |
self.image_aug = image_aug |
def calculate_loss(self, y_true, y_pred, mask): |
loss = self.loss(y_true, y_pred) |
mask = tf.cast(mask, dtype=loss.dtype) |
loss *= mask |
return tf.reduce_sum(loss) / tf.reduce_sum(mask) |
def calculate_accuracy(self, y_true, y_pred, mask): |
accuracy = tf.equal(y_true, tf.argmax(y_pred, axis=2)) |
accuracy = tf.math.logical_and(mask, accuracy) |
accuracy = tf.cast(accuracy, dtype=tf.float32) |
mask = tf.cast(mask, dtype=tf.float32) |
return tf.reduce_sum(accuracy) / tf.reduce_sum(mask) |
def _compute_caption_loss_and_acc(self, img_embed, batch_seq, training=True): |
encoder_out = self.encoder(img_embed, training=training) |
batch_seq_inp = batch_seq[:, :-1] |
batch_seq_true = batch_seq[:, 1:] |
mask = tf.math.not_equal(batch_seq_true, 0) |
batch_seq_pred = self.decoder( |
batch_seq_inp, encoder_out, training=training, mask=mask |
) |
loss = self.calculate_loss(batch_seq_true, batch_seq_pred, mask) |
acc = self.calculate_accuracy(batch_seq_true, batch_seq_pred, mask) |
return loss, acc |
def train_step(self, batch_data): |
batch_img, batch_seq = batch_data |
batch_loss = 0 |
batch_acc = 0 |
if self.image_aug: |
batch_img = self.image_aug(batch_img) |
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