def test_eager_flat_strict_upper_int_verification(self, data):
with eager_mode():
# sample square matrix
n = data.draw(st.integers(min_value=3, max_value=10))
input_ = data.draw(
np_st.arrays(dtype=np_st.integer_dtypes(), shape=(n, n)))
output = np.array(utils.flat_strict_upper(input_))
# verify
k = 0
for i in range(n):
for j in range(i + 1, n):
assert output[k] == input_[i, j]
k += 1
def test_flat_strict_upper_int_eager_graph_consistency(
self, int_graph, data, dtype):
# sample square matrix
n = data.draw(st.integers(min_value=3, max_value=10))
input_ = data.draw(np_st.arrays(dtype=dtype, shape=(n, n)))
# compute eager output
with eager_mode():
eager_output = utils.flat_strict_upper(input_)
# compute graph output
input_pl, output = int_graph
with tf.Session() as sess:
graph_output = sess.run(output, feed_dict={input_pl: input_})
np.testing.assert_equal(eager_output, graph_output)
def test_flat_strict_upper_float_eager_graph_consistency(
self, float_graph, data):
# sample square matrix
n = data.draw(st.integers(min_value=3, max_value=10))
elements = st.floats(allow_nan=False, allow_infinity=False, width=32)
input_ = data.draw(
np_st.arrays(dtype=np.float32, elements=elements, shape=(n, n)))
# compute eager output
with eager_mode():
eager_output = utils.flat_strict_upper(input_)
# compute graph output
input_pl, output = float_graph
with tf.Session() as sess:
graph_output = sess.run(output, feed_dict={input_pl: input_})
np.testing.assert_equal(eager_output, graph_output)
def test_eager_flat_strict_upper_float_verification(self, data):
with eager_mode():
# sample square matrix
n = data.draw(st.integers(min_value=3, max_value=10))
elements = st.floats(allow_nan=False,
allow_infinity=False,
width=32)
input_ = data.draw(
np_st.arrays(dtype=np.float32, elements=elements,
shape=(n, n)))
output = utils.flat_strict_upper(input_).numpy()
# verify
k = 0
for i in range(n):
for j in range(i + 1, n):
assert output[k] == input_[i, j]
k += 1
def histogram_loss(descriptors: tf.Tensor,
labels: tf.Tensor,
n_bins: int = 256) -> tf.Tensor:
"""Computes the histogram loss for the given `descriptors` and `labels`, with a `n_bins`-dimensional uniformly distributed histogram.
This function implements the loss described in:
["Learning Deep Embeddings with Histogram Loss". E. Ustinova, V. Lempitsky](https://arxiv.org/abs/1611.00822)
It differs from the proposed implementation because it computes the squared L2 distance between descriptors, instead of their dot product.
The loss to minimize, then, becomes the estimated probability of the distance of a negative pair to be less than the distance of a positive pair.
Since the descriptors are L2 normalized, the similarity S(d1, d2) = cos(d1, d2) between two descriptors d1 and d2 and their L2 distance D(d1, d2) are related via:
D(d1, d2) = 2 - 2 * acos(S(d1, d2))
The squared L2 distance between L2-normalized vectors is bounded to [0; 4] and the histogram is fit with `n_bins` bins uniformly distributed in this range.
Args:
descriptors: a `tf.Tensor` of `tf.float32` L2-normalized descriptors of shape `[batch_size, descriptor_dims]`.
labels: a `tf.Tensor` of `tf.int32` labels for the given descriptors. Its shape must be `[batch_size]`.
n_bins: an `int` indicating the number of bins to uniformly divide the range [0; 4].
Returns:
the histogram loss of the descriptors, computed with their L2 distances.
Raises:
ValueError: if `descriptors` has `ndmis` other than 2.
ValueError: if `labels` has `ndmis` other than 1.
ValueError: if `descriptors` and `labels` have incompatible shapes.
"""
with tf.name_scope('histogram_loss'):
descriptors = tf.convert_to_tensor(descriptors,
name='descriptors_input')
labels = tf.convert_to_tensor(labels, name='labels_input')
# check if descriptors have proper dims
descs_shape = descriptors.get_shape().as_list()
if len(descs_shape) != 2:
raise ValueError("expected descriptors ndmis=2, "
"found ndims={}. Full shape received: "
"{}.".format(descs_shape[0], descs_shape))
# check if labels have proper dims
labels_shape = labels.get_shape().as_list()
if len(labels_shape) != 1:
raise ValueError("expected labels ndmis=2, found "
"ndims={}. Full shape received: "
"{}.".format(labels_shape[0], labels_shape))
# check if descriptors and labels have compatible shapes
if descs_shape[0] is not None and labels_shape[0] is not None:
if descs_shape[0] != 1 and labels_shape[0] != 1:
if descs_shape[0] != labels_shape[0]:
raise ValueError("descriptors and labels have "
"incompatible first dimensions, "
"{} vs {}.".format(
descs_shape[0], labels_shape[0]))
# compute pairwise distances for l2-normalized descriptors
dists_mat = 2 - 2 * tf.matmul(descriptors, tf.transpose(descriptors))
dists = utils.flat_strict_upper(dists_mat)
# separate positive and negative pair distances
partitions_mat = tf.equal(labels, tf.expand_dims(labels, 1))
partitions = utils.flat_strict_upper(partitions_mat)
partitions = tf.cast(partitions, tf.int32)
neg_dists, pos_dists = tf.dynamic_partition(dists, partitions, 2)
# quantize [0; 4] range in n_bins bins
bins = tf.linspace(0.0, 4.0, n_bins)
bins = tf.expand_dims(bins, 0)
# compute positive pairs distance histogram
n_pos = tf.reduce_sum(partitions)
pos_dists = tf.expand_dims(pos_dists, 1)
pos_binned = 1 - (n_bins - 1) * tf.abs(pos_dists - bins) / 2
pos_binned = tf.nn.relu(pos_binned)
pos_hist = tf.reduce_sum(pos_binned, axis=0) / tf.cast(
n_pos, tf.float32)
# compute negative pairs distance histogram and cdf approximation
n_neg = tf.reduce_sum(1 - partitions)
neg_dists = tf.expand_dims(neg_dists, 1)
neg_binned = 1 - (n_bins - 1) * tf.abs(neg_dists - bins) / 2
neg_binned = tf.nn.relu(neg_binned)
neg_hist = tf.reduce_sum(neg_binned, axis=0) / tf.cast(
n_neg, tf.float32)
neg_cdf = tf.cumsum(neg_hist)
return tf.reduce_sum(pos_hist * neg_cdf)
def int_graph():
input_pl = tf.placeholder(tf.int64, [None, None])
output = utils.flat_strict_upper(input_pl)
yield input_pl, output
def test_flat_strict_upper_wrong_input_dims(self, shape):
assume(len(shape) != 2)
input_ = tf.placeholder(tf.int32, shape)
with pytest.raises(ValueError):
utils.flat_strict_upper(input_)