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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__ .. autoclass:: transformers.ForcedBOSTokenLogitsProcessor :members: __call__ .. autoclass:: transformers.ForcedEOSTokenLogitsProcessor :members: __call__ .. autoclass:: transformers.InfNanRemoveLogitsProcessor :members: __call__ StoppingCriteria ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ A :class:`~transformers.StoppingCriteria` can be used to change when to stop generation (other than EOS token). .. autoclass:: transformers.StoppingCriteria :members: __call__ .. autoclass:: transformers.StoppingCriteriaList :members: __call__ .. autoclass:: transformers.MaxLengthCriteria :members: __call__ .. autoclass:: transformers.MaxTimeCriteria :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