GPT2Tokenizer

• 원본 링크 : https://keras.io/api/keras_nlp/models/gpt2/gpt2_tokenizer/
• 최종 확인 : 2024-11-26

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GPT2Tokenizer class

keras_nlp.tokenizers.GPT2Tokenizer(vocabulary=None, merges=None, **kwargs)

A GPT-2 tokenizer using Byte-Pair Encoding subword segmentation.

This tokenizer class will tokenize raw strings into integer sequences and is based on keras_hub.tokenizers.BytePairTokenizer. Unlike the underlying tokenizer, it will check for all special tokens needed by GPT-2 models and provides a from_preset() method to automatically download a matching vocabulary for a GPT-2 preset.

If input is a batch of strings (rank > 0), the layer will output a tf.RaggedTensor where the last dimension of the output is ragged.

If input is a scalar string (rank == 0), the layer will output a dense tf.Tensor with static shape [None].

Arguments

• vocabulary: string or dict, maps token to integer ids. If it is a string, it should be the file path to a json file.
• merges: string or list, contains the merge rule. If it is a string, it should be the file path to merge rules. The merge rule file should have one merge rule per line. Every merge rule contains merge entities separated by a space.

Examples

# Unbatched input.
tokenizer = keras_hub.models.GPT2Tokenizer.from_preset("gpt2_base_en")
tokenizer("The quick brown fox jumped.")
# Batched input.
tokenizer(["The quick brown fox jumped.", "The fox slept."])
# Detokenization.
tokenizer.detokenize(tokenizer("The quick brown fox jumped."))
# Custom vocabulary.
vocab = {"<|endoftext|>": 0, "a": 4, "Ä quick": 5, "Ä fox": 6}
merges = ["Ä  q", "u i", "c k", "ui ck", "Ä q uick"]
merges += ["Ä  f", "o x", "Ä f ox"]
tokenizer = keras_hub.models.GPT2Tokenizer(vocabulary=vocab, merges=merges)
tokenizer("a quick fox.")

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from_preset method

GPT2Tokenizer.from_preset(preset, config_file="tokenizer.json", **kwargs)

Instantiate a keras_hub.models.Tokenizer from a model preset.

A preset is a directory of configs, weights and other file assets used to save and load a pre-trained model. The preset can be passed as one of:

1. a built-in preset identifier like 'bert_base_en'
2. a Kaggle Models handle like 'kaggle://user/bert/keras/bert_base_en'
3. a Hugging Face handle like 'hf://user/bert_base_en'
4. a path to a local preset directory like './bert_base_en'

For any Tokenizer subclass, you can run cls.presets.keys() to list all built-in presets available on the class.

This constructor can be called in one of two ways. Either from the base class like keras_hub.models.Tokenizer.from_preset(), or from a model class like keras_hub.models.GemmaTokenizer.from_preset(). If calling from the base class, the subclass of the returning object will be inferred from the config in the preset directory.

Arguments

• preset: string. A built-in preset identifier, a Kaggle Models handle, a Hugging Face handle, or a path to a local directory.
• load_weights: bool. If True, the weights will be loaded into the model architecture. If False, the weights will be randomly initialized.

Examples

# Load a preset tokenizer.
tokenizer = keras_hub.tokenizer.Tokenizer.from_preset("bert_base_en")
# Tokenize some input.
tokenizer("The quick brown fox tripped.")
# Detokenize some input.
tokenizer.detokenize([5, 6, 7, 8, 9])