constrative_function.py

def contrastive_loss_with_margin(margin=1):
    def contrastive_loss(y_true, y_pred):
        square_pred = K.square(y_pred)
        margin_square = K.square(K.maximum(margin - y_pred, 0))
        return (y_true * square_pred + (1 - y_true) * margin_square)
    return contrastive_loss