Add option to densely mask weighted_mean_absolute_error loss.

The same processing was applied las to `weighted_mean_squared_error`.

PiperOrigin-RevId: 684767761

scenic/model_lib/base_models/model_utils.py

@@ -30,8 +30,8 @@
 
 def psum_metric_normalizer(
     metrics: Tuple[jnp.ndarray, jnp.ndarray],
-    axis_name: Union[str,
-                     Tuple[str]] = 'batch') -> Tuple[jnp.ndarray, jnp.ndarray]:
+    axis_name: Union[str, Tuple[str, ...]] = 'batch'
+) -> Tuple[jnp.ndarray, jnp.ndarray]:
   """Applies psum over the given tuple of (metric, normalizer)."""
   psumed_metric = jax.lax.psum(jnp.sum(metrics[0]), axis_name=axis_name)
   psumed_normalizer = jax.lax.psum(jnp.sum(metrics[1]), axis_name=axis_name)
@@ -603,15 +603,15 @@ def weighted_squared_error(
   Args:
     predictions: Output of model in shape shape [batch, ..., n_features].
     targets: Array of shape [batch, ..., n_features].
-    weights:  None or array of shape [batch,] This is the weight to apply to the
-      loss computed for each example in the batch. Can be used to ignore padded
-      examples in the batch.
+    weights:  None or array of shape [batch, ...]. This is the weight to apply
+      to the loss computed for each example in the batch. Can be used to ignore
+      padded examples in the batch.
     axis: The axis (or axes) to compute the loss over. If not specified, all
       dimensions besides the leading batch dimension are used.
 
   Returns:
     The mean squared error for each example in the given batch. The output shape
-    is [batch,].
+    depends on axis.
   """
   if predictions.ndim != targets.ndim:
     raise ValueError(
@@ -671,7 +671,8 @@ def weighted_mean_squared_error(
 def weighted_absolute_error(
     predictions: jnp.ndarray,
     targets: jnp.ndarray,
-    weights: Optional[jnp.ndarray] = None) -> jnp.ndarray:
+    weights: Optional[jnp.ndarray] = None,
+    axis: Optional[Union[int, Tuple[int, ...]]] = None) -> jnp.ndarray:
   """Computes weighted absolute error given predictions and targets.
 
   This computes the absolute_error of examples in a single, potentially
@@ -682,23 +683,28 @@ def weighted_absolute_error(
   Args:
     predictions: Output of model in shape shape [batch, ..., n_features].
     targets: Array of shape [batch, ..., n_features].
-    weights:  None or array of shape [batch,] This is the weight to apply to the
-      loss  computed for each example in the batch. Can be used to ignore padded
-      examples in the batch.
+    weights:  None or array of shape [batch, ...] This is the weight to apply to
+      the loss  computed for each example in the batch. Can be used to ignore
+      padded examples in the batch.
+    axis: The axis (or axes) to compute the loss over. If not specified, all
+      dimensions besides the leading batch dimension are used.
 
   Returns:
     The mean absolute error for each example in the given batch. The output
-    shape is [batch,].
+    shape depends on axis.
   """
   if predictions.ndim != targets.ndim:
     raise ValueError(
         'Incorrect shapes. Got shape %s predictions and %s targets' %
         (str(predictions.shape), str(targets.shape)))
+  if axis is None:
+    # Sum over all features in each example in the batch:
+    axis = tuple(range(1, predictions.ndim))
 
   error = targets - predictions
   loss = jnp.absolute(error)
   # Sum over all features in each example in the batch:
-  loss = jnp.sum(loss, axis=tuple(range(1, predictions.ndim)))
+  loss = jnp.sum(loss, axis=axis)
   if weights is not None:
     loss = apply_weights(loss, weights)
   return loss
@@ -707,22 +713,25 @@ def weighted_absolute_error(
 def weighted_mean_absolute_error(
     predictions: jnp.ndarray,
     targets: jnp.ndarray,
-    weights: Optional[jnp.ndarray] = None) -> jnp.ndarray:
+    weights: Optional[jnp.ndarray] = None,
+    axis: Optional[Union[int, Tuple[int, ...]]] = None) -> jnp.ndarray:
   """Weighted mean of weighted_unnormalized_mean_absolute_error.
 
   Args:
     predictions: Output of model in shape [batch, ..., num_features].
     targets: Targets of shape [batch, ..., num_features].
-    weights:  None or array of shape [batch] This is the weight to apply to the
-      loss  computed for each example in the batch. Can be used to ignore padded
-      examples in the batch.
+    weights:  None or array of shape [batch, ...]. This is the weight to apply
+      to the loss  computed for each example in the batch. Can be used to ignore
+      padded examples in the batch.
+    axis: The axis (or axes) to compute the loss over. If not specified, all
+      dimensions besides the leading batch dimension are used.
 
   Returns:
     The averaged mean absolute error of all the examples in the given batch as
     a scalar.
   """
   unnormalized_mae = weighted_absolute_error(
-      predictions=predictions, targets=targets, weights=weights)
+      predictions=predictions, targets=targets, weights=weights, axis=axis)
 
   if weights is not None:
     # Divide by sum of weights: