C3W3_Assignment 3 - Error thrown just prior to end of first epoch

Course Q&A TensorFlow Developer Professional Natural Language Processing in TensorFlow
1

When trying to train the model (under a number of different architectures), I’m getting the following error just prior to the first epoch completing:

UnimplementedError: Cast string to float is not supported
[[node binary_crossentropy/Cast
(defined at /opt/conda/lib/python3.8/site-packages/keras/losses.py:1797)
]] [Op:__inference_test_function_64273]

Errors may have originated from an input operation.
Input Source operations connected to node binary_crossentropy/Cast:
In[0] ExpandDims (defined at /opt/conda/lib/python3.8/site-packages/keras/engine/compile_utils.py:677)

The cells at the start of the assignment are showing the expected outputs. Anyone else run into this issue and have suggestions on things I may be able to try to resolve?

2

Hello Raymond,

Can you share a screenshot of the image of your error without sharing any codes.

Kindly look at your model compile statement where your function call from strong to float is creating this error.

3

Labels should be numeric.

4

Hello Deepti,
The stack trace is pretty long. But here it is:
Epoch 1/20
4493/4500 [============================>.] - ETA: 0s - loss: 0.5779 - accuracy: 0.6899

UnimplementedError Traceback (most recent call last)
in
5
6 # Train the model and save the training history
----> 7 history = model.fit(train_pad_trunc_seq, train_labels, epochs=20, validation_data=(val_pad_trunc_seq, val_labels))

/opt/conda/lib/python3.8/site-packages/keras/utils/traceback_utils.py in error_handler(*args, **kwargs)
65 except Exception as e: # pylint: disable=broad-except
66 filtered_tb = _process_traceback_frames(e.traceback)
—> 67 raise e.with_traceback(filtered_tb) from None
68 finally:
69 del filtered_tb

/opt/conda/lib/python3.8/site-packages/tensorflow/python/eager/execute.py in quick_execute(op_name, num_outputs, inputs, attrs, ctx, name)
56 try:
57 ctx.ensure_initialized()
—> 58 tensors = pywrap_tfe.TFE_Py_Execute(ctx._handle, device_name, op_name,
59 inputs, attrs, num_outputs)
60 except core._NotOkStatusException as e:

UnimplementedError: Cast string to float is not supported
[[node binary_crossentropy/Cast
(defined at /opt/conda/lib/python3.8/site-packages/keras/losses.py:1797)
]] [Op:__inference_test_function_19035]

Errors may have originated from an input operation.
Input Source operations connected to node binary_crossentropy/Cast:
In[0] ExpandDims (defined at /opt/conda/lib/python3.8/site-packages/keras/engine/compile_utils.py:677)

Operation defined at: (most recent call last)

File “/opt/conda/lib/python3.8/runpy.py”, line 194, in _run_module_as_main
return _run_code(code, main_globals, None,

File “/opt/conda/lib/python3.8/runpy.py”, line 87, in _run_code
exec(code, run_globals)

File “/opt/conda/lib/python3.8/site-packages/ipykernel_launcher.py”, line 16, in
app.launch_new_instance()

File “/opt/conda/lib/python3.8/site-packages/traitlets/config/application.py”, line 845, in launch_instance
app.start()

File “/opt/conda/lib/python3.8/site-packages/ipykernel/kernelapp.py”, line 612, in start
self.io_loop.start()

File “/opt/conda/lib/python3.8/site-packages/tornado/platform/asyncio.py”, line 199, in start
self.asyncio_loop.run_forever()

File “/opt/conda/lib/python3.8/asyncio/base_events.py”, line 570, in run_forever
self._run_once()

File “/opt/conda/lib/python3.8/asyncio/base_events.py”, line 1859, in _run_once
handle._run()

File “/opt/conda/lib/python3.8/asyncio/events.py”, line 81, in _run
self._context.run(self._callback, *self._args)

File “/opt/conda/lib/python3.8/site-packages/tornado/ioloop.py”, line 688, in
lambda f: self._run_callback(functools.partial(callback, future))

File “/opt/conda/lib/python3.8/site-packages/tornado/ioloop.py”, line 741, in _run_callback
ret = callback()

File “/opt/conda/lib/python3.8/site-packages/tornado/gen.py”, line 814, in inner
self.ctx_run(self.run)

File “/opt/conda/lib/python3.8/site-packages/tornado/gen.py”, line 775, in run
yielded = self.gen.send(value)

File “/opt/conda/lib/python3.8/site-packages/ipykernel/kernelbase.py”, line 374, in dispatch_queue
yield self.process_one()

File “/opt/conda/lib/python3.8/site-packages/tornado/gen.py”, line 250, in wrapper
runner = Runner(ctx_run, result, future, yielded)

File “/opt/conda/lib/python3.8/site-packages/tornado/gen.py”, line 741, in init
self.ctx_run(self.run)

File “/opt/conda/lib/python3.8/site-packages/tornado/gen.py”, line 775, in run
yielded = self.gen.send(value)

File “/opt/conda/lib/python3.8/site-packages/ipykernel/kernelbase.py”, line 358, in process_one
yield gen.maybe_future(dispatch(*args))

File “/opt/conda/lib/python3.8/site-packages/tornado/gen.py”, line 234, in wrapper
yielded = ctx_run(next, result)

File “/opt/conda/lib/python3.8/site-packages/ipykernel/kernelbase.py”, line 261, in dispatch_shell
yield gen.maybe_future(handler(stream, idents, msg))

File “/opt/conda/lib/python3.8/site-packages/tornado/gen.py”, line 234, in wrapper
yielded = ctx_run(next, result)

File “/opt/conda/lib/python3.8/site-packages/ipykernel/kernelbase.py”, line 536, in execute_request
self.do_execute(

File “/opt/conda/lib/python3.8/site-packages/tornado/gen.py”, line 234, in wrapper
yielded = ctx_run(next, result)

File “/opt/conda/lib/python3.8/site-packages/ipykernel/ipkernel.py”, line 302, in do_execute
res = shell.run_cell(code, store_history=store_history, silent=silent)

File “/opt/conda/lib/python3.8/site-packages/ipykernel/zmqshell.py”, line 539, in run_cell
return super(ZMQInteractiveShell, self).run_cell(*args, **kwargs)

File “/opt/conda/lib/python3.8/site-packages/IPython/core/interactiveshell.py”, line 2894, in run_cell
result = self._run_cell(

File “/opt/conda/lib/python3.8/site-packages/IPython/core/interactiveshell.py”, line 2940, in _run_cell
return runner(coro)

File “/opt/conda/lib/python3.8/site-packages/IPython/core/async_helpers.py”, line 68, in _pseudo_sync_runner
coro.send(None)

File “/opt/conda/lib/python3.8/site-packages/IPython/core/interactiveshell.py”, line 3165, in run_cell_async
has_raised = await self.run_ast_nodes(code_ast.body, cell_name,

File “/opt/conda/lib/python3.8/site-packages/IPython/core/interactiveshell.py”, line 3357, in run_ast_nodes
if (await self.run_code(code, result, async_=asy)):

File “/opt/conda/lib/python3.8/site-packages/IPython/core/interactiveshell.py”, line 3437, in run_code
exec(code_obj, self.user_global_ns, self.user_ns)

File “”, line 7, in
history = model.fit(train_pad_trunc_seq, train_labels, epochs=20, validation_data=(val_pad_trunc_seq, val_labels))

File “/opt/conda/lib/python3.8/site-packages/keras/utils/traceback_utils.py”, line 64, in error_handler
return fn(*args, **kwargs)

File “/opt/conda/lib/python3.8/site-packages/keras/engine/training.py”, line 1252, in fit
val_logs = self.evaluate(

File “/opt/conda/lib/python3.8/site-packages/keras/utils/traceback_utils.py”, line 64, in error_handler
return fn(*args, **kwargs)

File “/opt/conda/lib/python3.8/site-packages/keras/engine/training.py”, line 1537, in evaluate
tmp_logs = self.test_function(iterator)

File “/opt/conda/lib/python3.8/site-packages/keras/engine/training.py”, line 1366, in test_function
return step_function(self, iterator)

File “/opt/conda/lib/python3.8/site-packages/keras/engine/training.py”, line 1356, in step_function
outputs = model.distribute_strategy.run(run_step, args=(data,))

File “/opt/conda/lib/python3.8/site-packages/keras/engine/training.py”, line 1349, in run_step
outputs = model.test_step(data)

File “/opt/conda/lib/python3.8/site-packages/keras/engine/training.py”, line 1305, in test_step
self.compiled_loss(

File “/opt/conda/lib/python3.8/site-packages/keras/engine/compile_utils.py”, line 201, in call
loss_value = loss_obj(y_t, y_p, sample_weight=sw)

File “/opt/conda/lib/python3.8/site-packages/keras/losses.py”, line 141, in call
losses = call_fn(y_true, y_pred)

File “/opt/conda/lib/python3.8/site-packages/keras/losses.py”, line 245, in call
return ag_fn(y_true, y_pred, **self._fn_kwargs)

File “/opt/conda/lib/python3.8/site-packages/keras/losses.py”, line 1797, in binary_crossentropy
y_true = tf.cast(y_true, y_pred.dtype)

5

The labels are of type int.

6

Apparently not. See here:

UnimplementedError: Cast string to float is not supported
[[node binary_crossentropy/Cast
(defined at /opt/conda/lib/python3.8/site-packages/keras/losses.py:1797)
]] [Op:__inference_test_function_19035]

and here:

File “/opt/conda/lib/python3.8/site-packages/keras/losses.py”, line 1797, in binary_crossentropy
y_true = tf.cast(y_true, y_pred.dtype)

If this doesn’t help, please click my name and message your notebook as an attachment.

1 Like
7

@balaji.ambresh Yep. You are correct. I accidentally set validation_labels to be sentences split on the training size instead of the labels with the appropriate split.

Oof. Thank you and Happy New Year!

1 Like
8

got exactly the same error, thanks for the answer mate.