l2_triplet_loss.py

# L2 Distance
def triplet_loss(alpha, emb_dim):
    def loss(y_true, y_pred):
        anc, pos, neg = y_pred[:,:emb_size], y_pred[:,emb_size:2*emb_size], y_pred[:,2*emb_size:]
        distance1 = tf.sqrt(tf.reduce_sum(tf.pow(anc - pos, 2), 1, keepdims=True))
        distance2 = tf.sqrt(tf.reduce_sum(tf.pow(anc - neg, 2), 1, keepdims=True))
        return tf.reduce_mean(tf.maximum(distance1 - distance2 + alpha, 0.))
    return loss