def test_correct_distance(self):
"""Compare against numpy caluclation."""
tf_embeddings = tf.constant([[0.5, 0.5], [1.0, 1.0]])
expected_distance = np.array([[0, np.sqrt(2) / 2], [np.sqrt(2) / 2, 0]])
distances = pairwise_distance(tf_embeddings, squared=False)
self.assertAllClose(expected_distance, distances)
def test_correct_distance_squared(self):
"""Compare against numpy caluclation for squared distances."""
tf_embeddings = tf.constant([[0.5, 0.5], [1.0, 1.0]])
expected_distance = np.array([[0, 0.5], [0.5, 0]])
distances = pairwise_distance(tf_embeddings, squared=True)
self.assertAllClose(expected_distance, distances)
def test_positive_distances(self):
"""Test that the pairwise distances are always positive."""
# Create embeddings very close to each other in [1.0 - 2e-7, 1.0 + 2e-7]
# This will encourage errors in the computation
embeddings = 1.0 + 2e-7 * tf.random.uniform([64, 6], dtype=tf.float32)
distances = pairwise_distance(embeddings, squared=False)
self.assertAllGreaterEqual(distances, 0)
def triplet_hard_loss(
y_true: TensorLike,
y_pred: TensorLike,
margin: FloatTensorLike = 1.0,
soft: bool = False,
) -> tf.Tensor:
"""Computes the triplet loss with hard negative and hard positive mining.
Args:
y_true: 1-D integer `Tensor` with shape [batch_size] of
multiclass integer labels.
y_pred: 2-D float `Tensor` of embedding vectors. Embeddings should
be l2 normalized.
margin: Float, margin term in the loss definition.
soft: Boolean, if set, use the soft margin version.
"""
labels, embeddings = y_true, y_pred
# Reshape label tensor to [batch_size, 1].
lshape = tf.shape(labels)
labels = tf.reshape(labels, [lshape[0], 1])
# Build pairwise squared distance matrix.
pdist_matrix = metric_learning.pairwise_distance(embeddings, squared=True)
# Build pairwise binary adjacency matrix.
adjacency = tf.math.equal(labels, tf.transpose(labels))
# Invert so we can select negatives only.
adjacency_not = tf.math.logical_not(adjacency)
adjacency_not = tf.cast(adjacency_not, dtype=tf.dtypes.float32)
# hard negatives: smallest D_an.
hard_negatives = _masked_minimum(pdist_matrix, adjacency_not)
batch_size = tf.size(labels)
adjacency = tf.cast(adjacency, dtype=tf.dtypes.float32)
mask_positives = tf.cast(adjacency, dtype=tf.dtypes.float32) - tf.linalg.diag(
tf.ones([batch_size])
)
# hard positives: largest D_ap.
hard_positives = _masked_maximum(pdist_matrix, mask_positives)
if soft:
triplet_loss = tf.math.log1p(tf.math.exp(hard_positives - hard_negatives))
else:
triplet_loss = tf.maximum(hard_positives - hard_negatives + margin, 0.0)
# Get final mean triplet loss
triplet_loss = tf.reduce_mean(triplet_loss)
return triplet_loss
def Quadruplet_loss(y_true, y_pred):
labels = tf.convert_to_tensor(y_true, name="labels")
embeddings = tf.convert_to_tensor(y_pred, name="embeddings")
pdist_matrix = metric_learning.pairwise_distance(embeddings, squared=False)
adjacency = tf.math.equal(labels, tf.transpose(labels))
# Invert so we can select negatives only.
adjacency_not = tf.math.logical_not(adjacency)
# cast to float32
adjacency_not = tf.cast(adjacency_not, dtype=tf.dtypes.float32)
adjacency = tf.cast(adjacency, dtype=tf.dtypes.float32)
# hard negatives: smallest D_an.
hard_negatives = _masked_minimum(pdist_matrix, adjacency_not)
# Remove negative from adjacency_not
adjacency_not2 = tf.math.equal(pdist_matrix, hard_negatives)
adjacency_not2 = tf.math.logical_not(adjacency_not2)
adjacency_not2 = tf.cast(adjacency_not2, dtype=tf.dtypes.float32)
adjacency_not2_2 = tf.math.multiply(adjacency_not, adjacency_not2)
hard_negatives2 = _masked_minimum(pdist_matrix, adjacency_not2_2)
# batch size of Training
batch_size = tf.size(labels)
mask_positives = adjacency - tf.linalg.diag(tf.ones([batch_size]))
# hard positives: largest D_ap.
hard_positives = _masked_maximum(pdist_matrix, mask_positives)
triplet_loss = tf.maximum(
(hard_positives * 2) - hard_negatives - hard_negatives2 + 0.2, 0.0)
return triplet_loss
def lifted_struct_loss(labels, embeddings, margin=1.0):
"""Computes the lifted structured loss.
Args:
labels: 1-D tf.int32 `Tensor` with shape [batch_size] of
multiclass integer labels.
embeddings: 2-D float `Tensor` of embedding vectors. Embeddings should
not be l2 normalized.
margin: Float, margin term in the loss definition.
Returns:
lifted_loss: tf.float32 scalar.
"""
# Reshape [batch_size] label tensor to a [batch_size, 1] label tensor.
lshape = tf.shape(labels)
assert lshape.shape == 1
labels = tf.reshape(labels, [lshape[0], 1])
# Build pairwise squared distance matrix.
pairwise_distances = metric_learning.pairwise_distance(embeddings)
# Build pairwise binary adjacency matrix.
adjacency = tf.math.equal(labels, tf.transpose(labels))
# Invert so we can select negatives only.
adjacency_not = tf.math.logical_not(adjacency)
batch_size = tf.size(labels)
diff = margin - pairwise_distances
mask = tf.cast(adjacency_not, dtype=tf.dtypes.float32)
# Safe maximum: Temporarily shift negative distances
# above zero before taking max.
# this is to take the max only among negatives.
row_minimums = tf.math.reduce_min(diff, 1, keepdims=True)
row_negative_maximums = tf.math.reduce_max(
tf.math.multiply(diff - row_minimums, mask), 1,
keepdims=True) + row_minimums
# Compute the loss.
# Keep track of matrix of maximums where M_ij = max(m_i, m_j)
# where m_i is the max of alpha - negative D_i's.
# This matches the Caffe loss layer implementation at:
# https://github.com/rksltnl/Caffe-Deep-Metric-Learning-CVPR16/blob/0efd7544a9846f58df923c8b992198ba5c355454/src/caffe/layers/lifted_struct_similarity_softmax_layer.cpp # pylint: disable=line-too-long
max_elements = tf.math.maximum(row_negative_maximums,
tf.transpose(row_negative_maximums))
diff_tiled = tf.tile(diff, [batch_size, 1])
mask_tiled = tf.tile(mask, [batch_size, 1])
max_elements_vect = tf.reshape(tf.transpose(max_elements), [-1, 1])
loss_exp_left = tf.reshape(
tf.math.reduce_sum(
tf.math.multiply(
tf.math.exp(diff_tiled - max_elements_vect), mask_tiled),
1,
keepdims=True), [batch_size, batch_size])
loss_mat = max_elements + tf.math.log(loss_exp_left +
tf.transpose(loss_exp_left))
# Add the positive distance.
loss_mat += pairwise_distances
mask_positives = tf.cast(
adjacency, dtype=tf.dtypes.float32) - tf.linalg.diag(
tf.ones([batch_size]))
# *0.5 for upper triangular, and another *0.5 for 1/2 factor for loss^2.
num_positives = tf.math.reduce_sum(mask_positives) / 2.0
lifted_loss = tf.math.truediv(
0.25 * tf.math.reduce_sum(
tf.math.square(
tf.math.maximum(
tf.math.multiply(loss_mat, mask_positives), 0.0))),
num_positives)
return lifted_loss
def call(self, y_true, y_pred):
from tensorflow_addons.losses import metric_learning
self.sd.update_state(y_true, y_pred)
labels = tf.cast(
tf.convert_to_tensor(y_true, name="labels"),
dtype=tf.dtypes.float32
)
if len(labels.shape) == 1:
labels = tf.reshape(labels, (1, -1))
embeddings = tf.convert_to_tensor(y_pred, name="embeddings")
convert_to_float32 = (
(embeddings.dtype == tf.dtypes.float16) or
(embeddings.dtype == tf.dtypes.bfloat16)
)
precise_embeddings = (
tf.cast(embeddings, tf.dtypes.float32)
if convert_to_float32
else embeddings
)
# Reshape label tensor to [batch_size, 1].
# lshape = tf.shape(labels)
# labels = tf.reshape(labels, [lshape[0], 1])
# Build pairwise squared distance matrix
distance_metric = self.distance_metric
if distance_metric == "L2":
pdist_matrix = metric_learning.pairwise_distance(
precise_embeddings, squared=False
)
elif distance_metric == "squared-L2":
pdist_matrix = metric_learning.pairwise_distance(
precise_embeddings, squared=True
)
elif distance_metric == "angular":
pdist_matrix = metric_learning.angular_distance(precise_embeddings)
else:
pdist_matrix = distance_metric(precise_embeddings)
# Fetch pairwise labels as adjacency matrix.
adjacency = self.response_diffs(labels)
# Invert so we can select negatives only.
adjacency_not = tf.math.logical_not(adjacency)
batch_size = tf.size(labels)
# Compute the mask.
pdist_matrix_tile = tf.tile(pdist_matrix, [batch_size, 1])
mask = tf.math.logical_and(
tf.tile(adjacency_not, [batch_size, 1]),
tf.math.greater(
pdist_matrix_tile,
tf.reshape(tf.transpose(pdist_matrix), [-1, 1])
),
)
mask_final = tf.reshape(
tf.math.greater(
tf.math.reduce_sum(
tf.cast(mask, dtype=tf.dtypes.float32),
1,
keepdims=True
),
0.0,
),
[batch_size, batch_size],
)
mask_final = tf.transpose(mask_final)
adjacency_not = tf.cast(adjacency_not, dtype=tf.dtypes.float32)
mask = tf.cast(mask, dtype=tf.dtypes.float32)
# negatives_outside: smallest D_an where D_an > D_ap.
negatives_outside = tf.reshape(
_masked_minimum(pdist_matrix_tile, mask), [batch_size, batch_size]
)
negatives_outside = tf.transpose(negatives_outside)
# negatives_inside: largest D_an.
negatives_inside = tf.tile(
_masked_maximum(pdist_matrix, adjacency_not), [1, batch_size]
)
semi_hard_negatives = tf.where(
mask_final,
negatives_outside,
negatives_inside
)
loss_mat = tf.math.add(self.margin, pdist_matrix - semi_hard_negatives)
mask_positives = (
tf.cast(adjacency, dtype=tf.dtypes.float32) -
tf.linalg.diag(tf.ones([batch_size]))
)
# In lifted-struct, the authors multiply 0.5 for upper triangular
# in semihard, they take all positive pairs except the diagonal.
# Max(n, 1) necessary to stop nan loss, which just stops the whole
# model from running.
# Setting to 1 will just mean zero loss, since everything
# else will be 0.
num_positives = tf.math.maximum(
tf.math.reduce_sum(mask_positives),
1.0
)
triplet_loss = tf.math.truediv(
tf.math.reduce_sum(
tf.math.maximum(
tf.math.multiply(loss_mat, mask_positives),
0.0
)
),
num_positives,
)
if convert_to_float32:
return tf.cast(triplet_loss, embeddings.dtype)
else:
return triplet_loss
def call(self, y_true, y_pred):
from tensorflow_addons.losses import metric_learning
self.sd.update_state(y_true, y_pred)
labels = tf.cast(
tf.convert_to_tensor(y_true, name="labels"),
dtype=tf.dtypes.float32
)
if len(labels.shape) == 1:
labels = tf.reshape(labels, (1, -1))
embeddings = tf.convert_to_tensor(y_pred, name="embeddings")
convert_to_float32 = (
(embeddings.dtype == tf.dtypes.float16) or
(embeddings.dtype == tf.dtypes.bfloat16)
)
precise_embeddings = (
tf.cast(embeddings, tf.dtypes.float32)
if convert_to_float32
else embeddings
)
# Reshape label tensor to [batch_size, 1].
# lshape = tf.shape(labels)
# labels = tf.reshape(labels, [lshape[0], 1])
# Build pairwise squared distance matrix
distance_metric = self.distance_metric
if distance_metric == "L2":
pdist_matrix = metric_learning.pairwise_distance(
precise_embeddings, squared=False
)
elif distance_metric == "squared-L2":
pdist_matrix = metric_learning.pairwise_distance(
precise_embeddings, squared=True
)
elif distance_metric == "angular":
pdist_matrix = metric_learning.angular_distance(precise_embeddings)
else:
pdist_matrix = distance_metric(precise_embeddings)
# Fetch pairwise labels as adjacency matrix.
adjacency = self.response_diffs(labels)
# Invert so we can select negatives only.
adjacency_not = tf.math.logical_not(adjacency)
adjacency = tf.cast(adjacency, dtype=tf.dtypes.float32)
adjacency_not = tf.cast(adjacency_not, dtype=tf.dtypes.float32)
hard_negatives = _masked_minimum(pdist_matrix, adjacency_not)
batch_size = tf.size(labels)
mask_positives = (
tf.cast(adjacency, dtype=tf.dtypes.float32) -
tf.linalg.diag(tf.ones([batch_size]))
)
# hard positives: largest D_ap.
hard_positives = _masked_maximum(pdist_matrix, mask_positives)
if self.soft:
triplet_loss = tf.math.log1p(
tf.math.exp(hard_positives - hard_negatives))
else:
triplet_loss = tf.maximum(
hard_positives - hard_negatives + self.margin,
0.0
)
# Get final mean triplet loss
triplet_loss = tf.reduce_mean(triplet_loss)
if convert_to_float32:
return tf.cast(triplet_loss, embeddings.dtype)
else:
return triplet_loss
def triplet_semihard_loss(
y_true: TensorLike,
y_pred: TensorLike,
margin: FloatTensorLike = 1.0,
distance_metric: Union[str, Callable] = "L2",
) -> tf.Tensor:
"""Computes the triplet loss with semi-hard negative mining.
Args:
y_true: 1-D integer `Tensor` with shape [batch_size] of
multiclass integer labels.
y_pred: 2-D float `Tensor` of embedding vectors. Embeddings should
be l2 normalized.
margin: Float, margin term in the loss definition.
distance_metric: str or function, determines distance metric:
"L2" for l2-norm distance
"squared-L2" for squared l2-norm distance
"angular" for cosine similarity
A custom function returning a 2d adjacency
matrix of a chosen distance metric can
also be passed here. e.g.
def custom_distance(batch):
batch = 1 - batch @ batch.T
return batch
triplet_semihard_loss(batch, labels,
distance_metric=custom_distance
)
Returns:
triplet_loss: float scalar with dtype of y_pred.
"""
labels, embeddings = y_true, y_pred
convert_to_float32 = (embeddings.dtype == tf.dtypes.float16
or embeddings.dtype == tf.dtypes.bfloat16)
precise_embeddings = (tf.cast(embeddings, tf.dtypes.float32)
if convert_to_float32 else embeddings)
# Reshape label tensor to [batch_size, 1].
lshape = tf.shape(labels)
labels = tf.reshape(labels, [lshape[0], 1])
# Build pairwise squared distance matrix
if distance_metric == "L2":
pdist_matrix = metric_learning.pairwise_distance(precise_embeddings,
squared=False)
elif distance_metric == "squared-L2":
pdist_matrix = metric_learning.pairwise_distance(precise_embeddings,
squared=True)
elif distance_metric == "angular":
pdist_matrix = metric_learning.angular_distance(precise_embeddings)
else:
pdist_matrix = distance_metric(precise_embeddings)
# Build pairwise binary adjacency matrix.
adjacency = tf.math.equal(labels, tf.transpose(labels))
# Invert so we can select negatives only.
adjacency_not = tf.math.logical_not(adjacency)
batch_size = tf.size(labels)
# Compute the mask.
pdist_matrix_tile = tf.tile(pdist_matrix, [batch_size, 1])
mask = tf.math.logical_and(
tf.tile(adjacency_not, [batch_size, 1]),
tf.math.greater(pdist_matrix_tile,
tf.reshape(tf.transpose(pdist_matrix), [-1, 1])),
)
mask_final = tf.reshape(
tf.math.greater(
tf.math.reduce_sum(tf.cast(mask, dtype=tf.dtypes.float32),
1,
keepdims=True),
0.0,
),
[batch_size, batch_size],
)
mask_final = tf.transpose(mask_final)
adjacency_not = tf.cast(adjacency_not, dtype=tf.dtypes.float32)
mask = tf.cast(mask, dtype=tf.dtypes.float32)
# negatives_outside: smallest D_an where D_an > D_ap.
negatives_outside = tf.reshape(_masked_minimum(pdist_matrix_tile, mask),
[batch_size, batch_size])
negatives_outside = tf.transpose(negatives_outside)
# negatives_inside: largest D_an.
negatives_inside = tf.tile(_masked_maximum(pdist_matrix, adjacency_not),
[1, batch_size])
semi_hard_negatives = tf.where(mask_final, negatives_outside,
negatives_inside)
loss_mat = tf.math.add(margin, pdist_matrix - semi_hard_negatives)
mask_positives = tf.cast(adjacency,
dtype=tf.dtypes.float32) - tf.linalg.diag(
tf.ones([batch_size]))
# In lifted-struct, the authors multiply 0.5 for upper triangular
# in semihard, they take all positive pairs except the diagonal.
num_positives = tf.math.reduce_sum(mask_positives)
triplet_loss = tf.math.truediv(
tf.math.reduce_sum(
tf.math.maximum(tf.math.multiply(loss_mat, mask_positives), 0.0)),
num_positives,
)
if convert_to_float32:
return tf.cast(triplet_loss, embeddings.dtype)
else:
return triplet_loss
def call(self, y_true, y_pred):
from tensorflow_addons.losses import metric_learning
self.sd.update_state(y_true, y_pred)
labels = tf.cast(
tf.convert_to_tensor(y_true, name="labels"),
dtype=tf.dtypes.float32
)
if len(labels.shape) == 1:
labels = tf.reshape(labels, (1, -1))
batch_size = tf.shape(labels)[0]
embeddings = tf.convert_to_tensor(y_pred, name="embeddings")
convert_to_float32 = (
(embeddings.dtype == tf.dtypes.float16) or
(embeddings.dtype == tf.dtypes.bfloat16)
)
precise_embeddings = (
tf.cast(embeddings, tf.dtypes.float32)
if convert_to_float32
else embeddings
)
# Reshape label tensor to [batch_size, 1].
# lshape = tf.shape(labels)
# labels = tf.reshape(labels, [lshape[0], 1])
# Build pairwise squared distance matrix
distance_metric = self.distance_metric
if distance_metric == "L2":
pdist_matrix = metric_learning.pairwise_distance(
precise_embeddings, squared=False
)
elif distance_metric == "squared-L2":
pdist_matrix = metric_learning.pairwise_distance(
precise_embeddings, squared=True
)
elif distance_metric == "angular":
pdist_matrix = metric_learning.angular_distance(precise_embeddings)
else:
pdist_matrix = distance_metric(precise_embeddings)
# Fetch pairwise labels as adjacency matrix.
adjacency = self.response_diffs(labels)
# Invert so we can select negatives only.
adjacency_not = tf.math.logical_not(adjacency)
radii = (
tf.reduce_mean(pdist_matrix, axis=1) -
(tf.math.reduce_std(pdist_matrix, axis=1) / 2.)
)
neighbors = tf.math.less(pdist_matrix, tf.reshape(radii, (-1, 1)))
hits = (
tf.cast(
tf.math.logical_and(neighbors, adjacency),
tf.dtypes.float32
) - tf.linalg.diag(tf.ones([batch_size]))
)
misses = tf.cast(
tf.math.logical_and(neighbors, adjacency_not),
tf.dtypes.float32
)
nhits = tf.reduce_sum(hits)
nmisses = tf.reduce_sum(misses)
n = tf.cast(batch_size, tf.dtypes.float32)
hits_dists = tf.multiply(pdist_matrix, hits)
hits_dists = tf.math.divide_no_nan(
hits_dists,
tf.math.multiply(n, nhits)
)
misses_dists = tf.multiply(pdist_matrix, misses)
misses_dists = tf.math.divide_no_nan(
misses_dists,
tf.math.multiply(n, nmisses)
)
loss = tf.subtract(misses_dists, hits_dists)
loss = tf.reduce_sum(loss, axis=1)
if convert_to_float32:
return tf.cast(loss, embeddings.dtype)
else:
return loss
def triplet_semihard_loss(y_true, y_pred, margin=1.0):
"""Computes the triplet loss with semi-hard negative mining.
Args:
y_true: 1-D integer `Tensor` with shape [batch_size] of
multiclass integer labels.
y_pred: 2-D float `Tensor` of embedding vectors. Embeddings should
be l2 normalized.
margin: Float, margin term in the loss definition.
"""
labels, embeddings = y_true, y_pred
# Reshape [batch_size] label tensor to a [batch_size, 1] label tensor.
lshape = tf.shape(labels)
assert lshape.shape == 1
labels = tf.reshape(labels, [lshape[0], 1])
# Build pairwise squared distance matrix.
pdist_matrix = metric_learning.pairwise_distance(embeddings, squared=True)
# Build pairwise binary adjacency matrix.
adjacency = tf.math.equal(labels, tf.transpose(labels))
# Invert so we can select negatives only.
adjacency_not = tf.math.logical_not(adjacency)
batch_size = tf.size(labels)
# Compute the mask.
pdist_matrix_tile = tf.tile(pdist_matrix, [batch_size, 1])
mask = tf.math.logical_and(
tf.tile(adjacency_not, [batch_size, 1]),
tf.math.greater(pdist_matrix_tile,
tf.reshape(tf.transpose(pdist_matrix), [-1, 1])))
mask_final = tf.reshape(
tf.math.greater(
tf.math.reduce_sum(tf.cast(mask, dtype=tf.dtypes.float32),
1,
keepdims=True), 0.0), [batch_size, batch_size])
mask_final = tf.transpose(mask_final)
adjacency_not = tf.cast(adjacency_not, dtype=tf.dtypes.float32)
mask = tf.cast(mask, dtype=tf.dtypes.float32)
# negatives_outside: smallest D_an where D_an > D_ap.
negatives_outside = tf.reshape(_masked_minimum(pdist_matrix_tile, mask),
[batch_size, batch_size])
negatives_outside = tf.transpose(negatives_outside)
# negatives_inside: largest D_an.
negatives_inside = tf.tile(_masked_maximum(pdist_matrix, adjacency_not),
[1, batch_size])
semi_hard_negatives = tf.where(mask_final, negatives_outside,
negatives_inside)
loss_mat = tf.math.add(margin, pdist_matrix - semi_hard_negatives)
mask_positives = tf.cast(adjacency,
dtype=tf.dtypes.float32) - tf.linalg.diag(
tf.ones([batch_size]))
# In lifted-struct, the authors multiply 0.5 for upper triangular
# in semihard, they take all positive pairs except the diagonal.
num_positives = tf.math.reduce_sum(mask_positives)
triplet_loss = tf.math.truediv(
tf.math.reduce_sum(
tf.math.maximum(tf.math.multiply(loss_mat, mask_positives), 0.0)),
num_positives)
return triplet_loss
def triplet_hard_loss(
y_true: TensorLike,
y_pred: TensorLike,
margin: FloatTensorLike = 1.0,
soft: bool = False,
distance_metric: Union[str, Callable] = "L2",
) -> tf.Tensor:
"""Computes the triplet loss with hard negative and hard positive mining.
Args:
y_true: 1-D integer `Tensor` with shape [batch_size] of
multiclass integer labels.
y_pred: 2-D float `Tensor` of embedding vectors. Embeddings should
be l2 normalized.
margin: Float, margin term in the loss definition.
soft: Boolean, if set, use the soft margin version.
distance_metric: str or function, determines distance metric:
"L2" for l2-norm distance
"squared-L2" for squared l2-norm distance
"angular" for cosine similarity
A custom function returning a 2d adjacency
matrix of a chosen distance metric can
also be passed here. e.g.
def custom_distance(batch):
batch = 1 - batch @ batch.T
return batch
triplet_semihard_loss(batch, labels,
distance_metric=custom_distance
)
Returns:
triplet_loss: float scalar with dtype of y_pred.
"""
labels, embeddings = y_true, y_pred
convert_to_float32 = (embeddings.dtype == tf.dtypes.float16
or embeddings.dtype == tf.dtypes.bfloat16)
precise_embeddings = (tf.cast(embeddings, tf.dtypes.float32)
if convert_to_float32 else embeddings)
# Reshape label tensor to [batch_size, 1].
lshape = tf.shape(labels)
labels = tf.reshape(labels, [lshape[0], 1])
# Build pairwise squared distance matrix.
if distance_metric == "L2":
pdist_matrix = metric_learning.pairwise_distance(precise_embeddings,
squared=False)
elif distance_metric == "squared-L2":
pdist_matrix = metric_learning.pairwise_distance(precise_embeddings,
squared=True)
elif distance_metric == "angular":
pdist_matrix = metric_learning.angular_distance(precise_embeddings)
else:
pdist_matrix = distance_metric(precise_embeddings)
# Build pairwise binary adjacency matrix.
adjacency = tf.math.equal(labels, tf.transpose(labels))
# Invert so we can select negatives only.
adjacency_not = tf.math.logical_not(adjacency)
adjacency_not = tf.cast(adjacency_not, dtype=tf.dtypes.float32)
# hard negatives: smallest D_an.
hard_negatives = _masked_minimum(pdist_matrix, adjacency_not)
batch_size = tf.size(labels)
adjacency = tf.cast(adjacency, dtype=tf.dtypes.float32)
mask_positives = tf.cast(adjacency,
dtype=tf.dtypes.float32) - tf.linalg.diag(
tf.ones([batch_size]))
# hard positives: largest D_ap.
hard_positives = _masked_maximum(pdist_matrix, mask_positives)
if soft:
triplet_loss = tf.math.log1p(
tf.math.exp(hard_positives - hard_negatives))
else:
triplet_loss = tf.maximum(hard_positives - hard_negatives + margin,
0.0)
# Get final mean triplet loss
triplet_loss = tf.reduce_mean(triplet_loss)
if convert_to_float32:
return tf.cast(triplet_loss, embeddings.dtype)
else:
return triplet_loss
def test_zero_distance():
"""Test that equal embeddings have a pairwise distance of 0."""
equal_embeddings = tf.constant([[1.0, 0.5], [1.0, 0.5]])
distances = pairwise_distance(equal_embeddings, squared=False)
np.testing.assert_allclose(tf.math.reduce_sum(distances), 0, 1e-6, 1e-6)
def call(self, inputs, **kwargs):
x_source, x_driving = inputs
kp_source_value, kp_source_jacobian = self.kp_extractor(x_source)
kp_driving_value, kp_driving_jacobian = self.kp_extractor(x_driving)
generated = {}
kp_driving_jacobian_inv = tf.linalg.inv(kp_driving_jacobian)
generated_prediction = self.generator(
(x_source, kp_driving_value, kp_driving_jacobian_inv,
kp_source_value, kp_source_jacobian))
generated.update({
'kp_source_value': kp_source_value,
'kp_driving_value': kp_driving_value,
'prediction': generated_prediction,
})
loss_values = {}
pyramide_real = self.pyramid(x_driving)
pyramide_generated = self.pyramid(generated_prediction)
# kp detector normalize loss
if self.use_kp_loss:
kp_source_loss = 0.
kp_driving_loss = 0.
kp_loss_koef = 0.7
for kp in kp_source_value:
distances = metric_learning.pairwise_distance(kp)
v, idx = tf.nn.top_k(-distances, 2)
mins = -v[:, 1] # 10
# tf.print(mins)
kp_source_loss += tf.reduce_sum(kp_loss_koef - mins)
for kp in kp_driving_value:
distances = metric_learning.pairwise_distance(kp)
v, idx = tf.nn.top_k(-distances, 2)
mins = -v[:, 1] # 10
# tf.print(mins)
kp_driving_loss += tf.reduce_sum(kp_loss_koef - mins)
kp_loss = (kp_source_loss + kp_driving_loss) / self.bs
loss_values['kp_loss'] = kp_loss * self.kp_loss_weight
if sum(self.loss_weights['perceptual']) != 0:
value_total = 0
for scale in self.scales:
x_vgg = self.vgg(pyramide_generated['prediction_' +
str(scale)])
y_vgg = self.vgg(pyramide_real['prediction_' + str(scale)])
for i, weight in enumerate(self.loss_weights['perceptual']):
value = tf.reduce_mean(
tf.abs(x_vgg[i] - tf.stop_gradient(y_vgg[i])))
value_total += self.loss_weights['perceptual'][i] * value
loss_values['perceptual'] = value_total
if self.loss_weights['generator_gan'] != 0:
discriminator_maps_generated = self.discriminator(
(pyramide_generated, tf.stop_gradient(kp_driving_value)))
discriminator_maps_real = self.discriminator(
(pyramide_real, tf.stop_gradient(kp_driving_value)))
value_total = 0
for scale in self.disc_scales:
key = f'prediction_map_{scale}'
value = tf.reduce_mean(
(1 - discriminator_maps_generated[key])**2)
value_total += self.loss_weights['generator_gan'] * value
loss_values['gen_gan'] = value_total
if sum(self.loss_weights['feature_matching']) != 0:
value_total = 0
for scale in self.disc_scales:
key = f'feature_maps_{scale}'
for i, (a, b) in enumerate(
zip(discriminator_maps_real[key],
discriminator_maps_generated[key])):
if self.loss_weights['feature_matching'][i] == 0:
continue
value = tf.reduce_mean(tf.abs(a - b))
value_total += self.loss_weights['feature_matching'][
i] * value
loss_values['feature_matching'] = value_total
if (self.loss_weights['equivariance_value'] +
self.loss_weights['equivariance_jacobian']) != 0:
# if self.transform is None:
# self.transform = Transform(x_driving.shape[0], **self.train_params['transform_params'])
transform = Transform(self.train_params['batch_size'],
**self.train_params['transform_params'])
transformed_frame = transform.transform_frame(x_driving)
transformed_kp_value, transformed_kp_jacobian = self.kp_extractor(
transformed_frame)
# generated['transformed_frame'] = transformed_frame
# generated['transformed_kp_value'] = transformed_kp_value
# generated['transformed_kp_jacobian'] = transformed_kp_jacobian
# Value loss part
if self.loss_weights['equivariance_value'] != 0:
value = tf.reduce_mean(
tf.abs(kp_driving_value -
transform.warp_coordinates(transformed_kp_value)))
loss_values['equivariance_value'] = self.loss_weights[
'equivariance_value'] * value
# jacobian loss part
if self.loss_weights['equivariance_jacobian'] != 0:
jacobian_transformed = tf.matmul(
transform.jacobian(transformed_kp_value, self.grad_tape),
transformed_kp_jacobian)
normed_driving = tf.linalg.inv(kp_driving_jacobian)
normed_transformed = jacobian_transformed
value = tf.matmul(normed_driving, normed_transformed)
eye = tf.reshape(tf.eye(2), [1, 1, 2, 2])
value = tf.reduce_mean(tf.abs(eye - value))
loss_values['equivariance_jacobian'] = self.loss_weights[
'equivariance_jacobian'] * value
return loss_values, generated
def test_zero_distance(self):
"""Test that equal embeddings have a pairwise distance of 0."""
equal_embeddings = tf.constant([[1.0, 0.5], [1.0, 0.5]])
distances = pairwise_distance(equal_embeddings, squared=False)
self.assertAllClose(tf.math.reduce_sum(distances), 0)
def triplet_semihard_loss(
y_true: TensorLike,
y_pred: TensorLike,
margin: FloatTensorLike = 1.0,
distance_metric: Union[str, Callable] = "L2",
) -> tf.Tensor:
r"""Computes the triplet loss with semi-hard negative mining.
Usage:
>>> y_true = tf.convert_to_tensor([0, 0])
>>> y_pred = tf.convert_to_tensor([[0.0, 1.0], [1.0, 0.0]])
>>> tfa.losses.triplet_semihard_loss(y_true, y_pred, distance_metric="L2")
<tf.Tensor: shape=(), dtype=float32, numpy=2.4142137>
>>> # Calling with callable `distance_metric`
>>> distance_metric = lambda x: tf.linalg.matmul(x, x, transpose_b=True)
>>> tfa.losses.triplet_semihard_loss(y_true, y_pred, distance_metric=distance_metric)
<tf.Tensor: shape=(), dtype=float32, numpy=1.0>
Args:
y_true: 1-D integer `Tensor` with shape `[batch_size]` of
multiclass integer labels.
y_pred: 2-D float `Tensor` of embedding vectors. Embeddings should
be l2 normalized.
margin: Float, margin term in the loss definition.
distance_metric: `str` or a `Callable` that determines distance metric.
Valid strings are "L2" for l2-norm distance,
"squared-L2" for squared l2-norm distance,
and "angular" for cosine similarity.
A `Callable` should take a batch of embeddings as input and
return the pairwise distance matrix.
Returns:
triplet_loss: float scalar with dtype of `y_pred`.
"""
labels, embeddings = y_true, y_pred
convert_to_float32 = (embeddings.dtype == tf.dtypes.float16
or embeddings.dtype == tf.dtypes.bfloat16)
precise_embeddings = (tf.cast(embeddings, tf.dtypes.float32)
if convert_to_float32 else embeddings)
# Reshape label tensor to [batch_size, 1].
lshape = tf.shape(labels)
labels = tf.reshape(labels, [lshape[0], 1])
# Build pairwise squared distance matrix
if distance_metric == "L2":
pdist_matrix = metric_learning.pairwise_distance(precise_embeddings,
squared=False)
elif distance_metric == "squared-L2":
pdist_matrix = metric_learning.pairwise_distance(precise_embeddings,
squared=True)
elif distance_metric == "angular":
pdist_matrix = metric_learning.angular_distance(precise_embeddings)
else:
pdist_matrix = distance_metric(precise_embeddings)
# Build pairwise binary adjacency matrix.
adjacency = tf.math.equal(labels, tf.transpose(labels))
# Invert so we can select negatives only.
adjacency_not = tf.math.logical_not(adjacency)
batch_size = tf.size(labels)
# Compute the mask.
pdist_matrix_tile = tf.tile(pdist_matrix, [batch_size, 1])
mask = tf.math.logical_and(
tf.tile(adjacency_not, [batch_size, 1]),
tf.math.greater(pdist_matrix_tile,
tf.reshape(tf.transpose(pdist_matrix), [-1, 1])),
)
mask_final = tf.reshape(
tf.math.greater(
tf.math.reduce_sum(tf.cast(mask, dtype=tf.dtypes.float32),
1,
keepdims=True),
0.0,
),
[batch_size, batch_size],
)
mask_final = tf.transpose(mask_final)
adjacency_not = tf.cast(adjacency_not, dtype=tf.dtypes.float32)
mask = tf.cast(mask, dtype=tf.dtypes.float32)
# negatives_outside: smallest D_an where D_an > D_ap.
negatives_outside = tf.reshape(_masked_minimum(pdist_matrix_tile, mask),
[batch_size, batch_size])
negatives_outside = tf.transpose(negatives_outside)
# negatives_inside: largest D_an.
negatives_inside = tf.tile(_masked_maximum(pdist_matrix, adjacency_not),
[1, batch_size])
semi_hard_negatives = tf.where(mask_final, negatives_outside,
negatives_inside)
loss_mat = tf.math.add(margin, pdist_matrix - semi_hard_negatives)
mask_positives = tf.cast(adjacency,
dtype=tf.dtypes.float32) - tf.linalg.diag(
tf.ones([batch_size]))
# In lifted-struct, the authors multiply 0.5 for upper triangular
# in semihard, they take all positive pairs except the diagonal.
num_positives = tf.math.reduce_sum(mask_positives)
triplet_loss = tf.math.truediv(
tf.math.reduce_sum(
tf.math.maximum(tf.math.multiply(loss_mat, mask_positives), 0.0)),
num_positives,
)
if convert_to_float32:
return tf.cast(triplet_loss, embeddings.dtype)
else:
return triplet_loss
def triplet_hard_loss(
y_true: TensorLike,
y_pred: TensorLike,
margin: FloatTensorLike = 1.0,
soft: bool = False,
distance_metric: Union[str, Callable] = "L2",
) -> tf.Tensor:
r"""Computes the triplet loss with hard negative and hard positive mining.
Usage:
>>> y_true = tf.convert_to_tensor([0, 0])
>>> y_pred = tf.convert_to_tensor([[0.0, 1.0], [1.0, 0.0]])
>>> tfa.losses.triplet_hard_loss(y_true, y_pred, distance_metric="L2")
<tf.Tensor: shape=(), dtype=float32, numpy=1.0>
>>> # Calling with callable `distance_metric`
>>> distance_metric = lambda x: tf.linalg.matmul(x, x, transpose_b=True)
>>> tfa.losses.triplet_hard_loss(y_true, y_pred, distance_metric=distance_metric)
<tf.Tensor: shape=(), dtype=float32, numpy=0.0>
Args:
y_true: 1-D integer `Tensor` with shape `[batch_size]` of
multiclass integer labels.
y_pred: 2-D float `Tensor` of embedding vectors. Embeddings should
be l2 normalized.
margin: Float, margin term in the loss definition.
soft: Boolean, if set, use the soft margin version.
distance_metric: `str` or a `Callable` that determines distance metric.
Valid strings are "L2" for l2-norm distance,
"squared-L2" for squared l2-norm distance,
and "angular" for cosine similarity.
A `Callable` should take a batch of embeddings as input and
return the pairwise distance matrix.
Returns:
triplet_loss: float scalar with dtype of `y_pred`.
"""
labels, embeddings = y_true, y_pred
convert_to_float32 = (embeddings.dtype == tf.dtypes.float16
or embeddings.dtype == tf.dtypes.bfloat16)
precise_embeddings = (tf.cast(embeddings, tf.dtypes.float32)
if convert_to_float32 else embeddings)
# Reshape label tensor to [batch_size, 1].
lshape = tf.shape(labels)
labels = tf.reshape(labels, [lshape[0], 1])
# Build pairwise squared distance matrix.
if distance_metric == "L2":
pdist_matrix = metric_learning.pairwise_distance(precise_embeddings,
squared=False)
elif distance_metric == "squared-L2":
pdist_matrix = metric_learning.pairwise_distance(precise_embeddings,
squared=True)
elif distance_metric == "angular":
pdist_matrix = metric_learning.angular_distance(precise_embeddings)
else:
pdist_matrix = distance_metric(precise_embeddings)
# Build pairwise binary adjacency matrix.
adjacency = tf.math.equal(labels, tf.transpose(labels))
# Invert so we can select negatives only.
adjacency_not = tf.math.logical_not(adjacency)
adjacency_not = tf.cast(adjacency_not, dtype=tf.dtypes.float32)
# hard negatives: smallest D_an.
hard_negatives = _masked_minimum(pdist_matrix, adjacency_not)
batch_size = tf.size(labels)
adjacency = tf.cast(adjacency, dtype=tf.dtypes.float32)
mask_positives = tf.cast(adjacency,
dtype=tf.dtypes.float32) - tf.linalg.diag(
tf.ones([batch_size]))
# hard positives: largest D_ap.
hard_positives = _masked_maximum(pdist_matrix, mask_positives)
if soft:
triplet_loss = tf.math.log1p(
tf.math.exp(hard_positives - hard_negatives))
else:
triplet_loss = tf.maximum(hard_positives - hard_negatives + margin,
0.0)
# Get final mean triplet loss
triplet_loss = tf.reduce_mean(triplet_loss)
if convert_to_float32:
return tf.cast(triplet_loss, embeddings.dtype)
else:
return triplet_loss