Custom Loss Function

Tensorleap enables you to write custom loss functions to be used within the platform. Once you define your custom loss function, and add it using add_custom_loss, you can use it within the platform by adding a CustomLoss node.

This function has two parameters y_true (tf.Tensor) and y_pred (tf.Tensor) which are correlated with the CustomLoss node's ground truth and prediction input tensors. These are of shape (batch, dim-1,...,dim-n). The function returns a tf.Tensor that contains either an aggregated value or loss calculated for each sample within the batch. While training, this tensor is averaged to be considered as the overall batch loss.

Example a custom loss function:

def weighted_categorical_crossentropy(y_true: tf.Tensor, y_pred: tf.Tensor) -> tf.Tensor:
    # scale predictions so that the class probas of each sample sum to 1
    y_pred /= K.sum(y_pred, axis=-1, keepdims=True)
    # clip to prevent NaN's and Inf's
    y_pred = K.clip(y_pred, K.epsilon(), 1 - K.epsilon())
    # calc

    weights = np.array([0.5, 2.1, 3, 4, 4, 4, 4, 4])
    loss = y_true * K.log(y_pred) * weights
    loss = -K.sum(loss, -1)
    return loss

The leap_binder then adds the function above to the list of custom loss functions by calling the add_custom_loss function.

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