ListMapper does not support model.save

[pedro-r-marques]

Got a stack trace when attempting to save model.

~/src/keras-list-mapper/keras_list_mapper/keras_list_mapper.py in __call__(self, inputs, *args, **kwargs)
     85             K.is_keras_tensor(t) for t in inputs_list)
     86         if not in_functional_construction_mode:
---> 87             return super().__call__(inputs)
     88 
     89         inner_inputs = []

~/src/keras-list-mapper/.venv/lib/python3.7/site-packages/tensorflow/python/keras/engine/base_layer.py in __call__(self, *args, **kwargs)
    983     #  signature
    984     # (5) False (treating the layer as if it's in inference)
--> 985     args, kwargs, training_mode = self._set_training_mode(
    986         args, kwargs, call_context)
    987 

~/src/keras-list-mapper/.venv/lib/python3.7/site-packages/tensorflow/python/autograph/impl/api.py in wrapper(*args, **kwargs)
    300     setattr(entity.__func__, 'autograph_info__', extras)
    301   else:
--> 302     setattr(entity, 'autograph_info__', extras)
    303   return entity
    304 

~/src/keras-list-mapper/keras_list_mapper/keras_list_mapper.py in call(self, inputs, *args, **kwargs)
    157         row_lengths = rt.row_lengths()
    158         max_seq_len = input_rt_shape[1]
--> 159         for i in tf.range(max_seq_len):
    160             indices = tf.where(tf.math.less(i, row_lengths))
    161             xcol = tf.fill([tf.shape(indices)[0]], i)

~/src/keras-list-mapper/.venv/lib/python3.7/site-packages/tensorflow/python/framework/ops.py in __iter__(self)
    501       # Default: V1-style Graph execution.
    502       self._disallow_in_graph_mode("iterating over `tf.Tensor`")
--> 503 
    504   def __iter__(self):
    505     if not context.executing_eagerly():

~/src/keras-list-mapper/.venv/lib/python3.7/site-packages/tensorflow/python/framework/ops.py in _disallow_iteration(self)
    492       # Default: V1-style Graph execution.
    493       self._disallow_in_graph_mode("using a `tf.Tensor` as a Python `bool`")
--> 494 
    495   def _disallow_iteration(self):
    496     if ag_ctx.control_status_ctx().status == ag_ctx.Status.DISABLED:

~/src/keras-list-mapper/.venv/lib/python3.7/site-packages/tensorflow/python/framework/ops.py in _disallow_when_autograph_disabled(self, task)
    467         "Tensor._shape cannot be assigned, use Tensor.set_shape instead.")
    468 
--> 469   def _disallow_when_autograph_disabled(self, task):
    470     raise errors.OperatorNotAllowedInGraphError(
    471         "{} is not allowed: AutoGraph is disabled in this function."

OperatorNotAllowedInGraphError: iterating over `tf.Tensor` is not allowed: AutoGraph is disabled in this function. Try decorating it directly with @tf.function.

[pedro-r-marques]

Saving of models with layers that return ragged tensors seems to not be currently supported tensorflow/tensorflow#45797