tfa.losses.contrastive_loss

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Computes the contrastive loss between y_true and y_pred.

@tf.function
tfa.losses.contrastive_loss(
    y_true: tfa.types.TensorLike,
    y_pred: tfa.types.TensorLike,
    margin: tfa.types.Number = 1.0
) -> tf.Tensor

This loss encourages the embedding to be close to each other for the samples of the same label and the embedding to be far apart at least by the margin constant for the samples of different labels.

The euclidean distances y_pred between two embedding matrices a and b with shape [batch_size, hidden_size] can be computed as follows:

a = tf.constant([[1, 2],
                [3, 4],
                [5, 6]], dtype=tf.float16)
b = tf.constant([[5, 9],
                [3, 6],
                [1, 8]], dtype=tf.float16)
y_pred = tf.linalg.norm(a - b, axis=1)
y_pred
<tf.Tensor: shape=(3,), dtype=float16, numpy=array([8.06 , 2.   , 4.473],
dtype=float16)>

<... Note: constants a & b have been used purely for example purposes and have no significant value ...>

See: http://yann.lecun.com/exdb/publis/pdf/hadsell-chopra-lecun-06.pdf

Args
y_true	1-D integer Tensor with shape [batch_size] of binary labels indicating positive vs negative pair.
y_pred	1-D float Tensor with shape [batch_size] of distances between two embedding matrices.
margin	margin term in the loss definition.

Returns
contrastive_loss	1-D float Tensor with shape [batch_size].