transformers/docs/source/internal/generation_utils.rst
Simon Brandeis c89f1bc92e
Add flags to return scores, hidden states and / or attention weights in GenerationMixin (#9150)
* Define new output dataclasses for greedy generation

* Add output_[...] flags in greedy generation methods

Added output_attentions, output_hidden_states, output_scores flags in
generate and greedy_search methods in GenerationMixin.

* [WIP] Implement logic and tests for output flags in generation

* Update GreedySearchOutput classes & docstring

* Implement greedy search output accumulation logic

Update greedy_search unittests

Fix generate method return value docstring

Properly init flags with the default config

* Update configuration to add output_scores flag

* Fix test_generation_utils

Sort imports and fix isinstance tests for GreedySearchOutputs

* Fix typo in generation_utils

* Add return_dict_in_generate for backwards compatibility

* Add return_dict_in_generate flag in config

* Fix tyPo in configuration

* Fix handling of attentions and hidden_states flags

* Make style & quality

* first attempt attentions

* some corrections

* improve tests

* special models requires special test

* disable xlm test for now

* clean tests

* fix for tf

* isort

* Add output dataclasses for other generation methods

* Add logic to return dict in sample generation

* Complete test for sample generation

- Pass output_attentions and output_hidden_states flags to encoder in
encoder-decoder models
- Fix import satements order in test_generation_utils file

* Add logic to return dict in sample generation

- Refactor tests to avoid using self.assertTrue, which provides
scarce information when the test fails
- Add tests for the three beam_search methods: vanilla, sample and
grouped

* Style doc

* Fix copy-paste error in generation tests

* Rename logits to scores and refactor

* Refactor group_beam_search for consistency

* make style

* add sequences_scores

* fix all tests

* add docs

* fix beam search finalize test

* correct docstring

* clean some files

* Made suggested changes to the documentation

* Style doc ?

* Style doc using the Python util

* Update src/transformers/generation_utils.py

* fix empty lines

* fix all test

Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>
2021-01-06 17:11:42 +01:00

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..
Copyright 2020 The HuggingFace Team. All rights reserved.
Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
specific language governing permissions and limitations under the License.
Utilities for Generation
-----------------------------------------------------------------------------------------------------------------------
This page lists all the utility functions used by :meth:`~transformers.PreTrainedModel.generate`,
:meth:`~transformers.PreTrainedModel.greedy_search`, :meth:`~transformers.PreTrainedModel.sample`,
:meth:`~transformers.PreTrainedModel.beam_search`, :meth:`~transformers.PreTrainedModel.beam_sample`, and
:meth:`~transformers.PreTrainedModel.group_beam_search`.
Most of those are only useful if you are studying the code of the generate methods in the library.
Generate Outputs
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The output of :meth:`~transformers.PreTrainedModel.generate` is an instance of a subclass of
:class:`~transformers.file_utils.ModelOutput`. This output is a data structure containing all the information returned
by :meth:`~transformers.PreTrainedModel.generate`, but that can also be used as tuple or dictionary.
Here's an example:
.. code-block::
from transformers import GPT2Tokenizer, GPT2LMHeadModel
tokenizer = GPT2Tokenizer.from_pretrained('gpt2')
model = GPT2LMHeadModel.from_pretrained('gpt2')
inputs = tokenizer("Hello, my dog is cute and ", return_tensors="pt")
generation_output = model.generate(**inputs, return_dict_in_generate=True, output_scores=True)
The ``generation_output`` object is a :class:`~transformers.generation_utils.GreedySearchDecoderOnlyOutput`, as we can
see in the documentation of that class below, it means it has the following attributes:
- ``sequences``: the generated sequences of tokens
- ``scores`` (optional): the prediction scores of the language modelling head, for each generation step
- ``hidden_states`` (optional): the hidden states of the model, for each generation step
- ``attentions`` (optional): the attention weights of the model, for each generation step
Here we have the ``scores`` since we passed along ``output_scores=True``, but we don't have ``hidden_states`` and
``attentions`` because we didn't pass ``output_hidden_states=True`` or ``output_attentions=True``.
You can access each attribute as you would usually do, and if that attribute has not been returned by the model, you
will get ``None``. Here for instance ``generation_output.scores`` are all the generated prediction scores of the
language modeling head, and ``generation_output.attentions`` is ``None``.
When using our ``generation_output`` object as a tuple, it only keeps the attributes that don't have ``None`` values.
Here, for instance, it has two elements, ``loss`` then ``logits``, so
.. code-block::
generation_output[:2]
will return the tuple ``(generation_output.sequences, generation_output.scores)`` for instance.
When using our ``generation_output`` object as a dictionary, it only keeps the attributes that don't have ``None``
values. Here, for instance, it has two keys that are ``sequences`` and ``scores``.
We document here all output types.
GreedySearchOutput
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
.. autoclass:: transformers.generation_utils.GreedySearchDecoderOnlyOutput
:members:
.. autoclass:: transformers.generation_utils.GreedySearchEncoderDecoderOutput
:members:
SampleOutput
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
.. autoclass:: transformers.generation_utils.SampleDecoderOnlyOutput
:members:
.. autoclass:: transformers.generation_utils.SampleEncoderDecoderOutput
:members:
BeamSearchOutput
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
.. autoclass:: transformers.generation_utils.BeamSearchDecoderOnlyOutput
:members:
.. autoclass:: transformers.generation_utils.BeamSearchEncoderDecoderOutput
:members:
BeamSampleOutput
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
.. autoclass:: transformers.generation_utils.BeamSampleDecoderOnlyOutput
:members:
.. autoclass:: transformers.generation_utils.BeamSampleEncoderDecoderOutput
:members:
LogitsProcessor
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
A :class:`~transformers.LogitsProcessor` can be used to modify the prediction scores of a language model head for
generation.
.. autoclass:: transformers.LogitsProcessor
:members: __call__
.. autoclass:: transformers.LogitsProcessorList
:members: __call__
.. autoclass:: transformers.LogitsWarper
:members: __call__
.. autoclass:: transformers.MinLengthLogitsProcessor
:members: __call__
.. autoclass:: transformers.TemperatureLogitsWarper
:members: __call__
.. autoclass:: transformers.RepetitionPenaltyLogitsProcessor
:members: __call__
.. autoclass:: transformers.TopPLogitsWarper
:members: __call__
.. autoclass:: transformers.TopKLogitsWarper
:members: __call__
.. autoclass:: transformers.NoRepeatNGramLogitsProcessor
:members: __call__
.. autoclass:: transformers.NoBadWordsLogitsProcessor
:members: __call__
.. autoclass:: transformers.PrefixConstrainedLogitsProcessor
:members: __call__
.. autoclass:: transformers.HammingDiversityLogitsProcessor
:members: __call__
BeamSearch
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.. autoclass:: transformers.BeamScorer
:members: process, finalize
.. autoclass:: transformers.BeamSearchScorer
:members: process, finalize
Utilities
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.. autofunction:: transformers.top_k_top_p_filtering
.. autofunction:: transformers.tf_top_k_top_p_filtering