Qwen3CausalLMPreprocessor layer

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Qwen3CausalLMPreprocessor class

keras_hub.models.Qwen3CausalLMPreprocessor(
    tokenizer, sequence_length=1024, add_start_token=True, add_end_token=True, **kwargs
)

Base class for causal language modeling preprocessing layers.

CausalLMPreprocessor tasks wrap a keras_hub.tokenizer.Tokenizer to create a preprocessing layer for causal language modeling tasks. It is intended to be paired with a keras.models.CausalLM task.

All CausalLMPreprocessor take inputs a single input. This can be a single string or a batch of strings. See examples below. These inputs will be tokenized and padded/truncated to a fixed sequence length.

This layer will always output a (x, y, sample_weight) tuple, where x is a dictionary with the tokenized inputs, y contains the tokens from x offset by 1, and sample_weight marks where y contains padded values. The exact contents of x will vary depending on the model being used.

a CausalLMPreprocessor contains two extra methods, generate_preprocess and generate_postprocess for use with generation. See examples below.

All CausalLMPreprocessor tasks include a from_preset() constructor which can be used to load a pre-trained config and vocabularies. You can call the from_preset() constructor directly on this base class, in which case the correct class for you model will be automatically instantiated.

Examples.

preprocessor = keras_hub.models.CausalLMPreprocessor.from_preset(
    "bert_base_en_uncased",
    sequence_length=256, # Optional.
)

# Tokenize, mask and pack a single sentence.
x = "The quick brown fox jumped."
x, y, sample_weight = preprocessor(x)

# Tokenize and pad/truncate a batch of labeled sentences.
x = ["The quick brown fox jumped.", "Call me Ishmael."]
x, y, sample_weight = preprocessor(x)

# With a [`tf.data.Dataset`](https://www.tensorflow.org/api_docs/python/tf/data/Dataset).
ds = tf.data.Dataset.from_tensor_slices(x)
ds = ds.map(preprocessor, num_parallel_calls=tf.data.AUTOTUNE)

# Generate preprocess and postprocess.
x = preprocessor.generate_preprocess(x)  # Tokenized numeric inputs.
x = preprocessor.generate_postprocess(x)  # Detokenized string outputs.

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from_preset method

Qwen3CausalLMPreprocessor.from_preset(
    preset, config_file="preprocessor.json", **kwargs
)

Instantiate a keras_hub.models.Preprocessor 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 Preprocessor subclass, you can run cls.presets.keys() to list all built-in presets available on the class.

As there are usually multiple preprocessing classes for a given model, this method should be called on a specific subclass like keras_hub.models.BertTextClassifierPreprocessor.from_preset().

Arguments

• preset: string. A built-in preset identifier, a Kaggle Models handle, a Hugging Face handle, or a path to a local directory.

Examples

# Load a preprocessor for Gemma generation.
preprocessor = keras_hub.models.CausalLMPreprocessor.from_preset(
    "gemma_2b_en",
)

# Load a preprocessor for Bert classification.
preprocessor = keras_hub.models.TextClassifierPreprocessor.from_preset(
    "bert_base_en",
)

tokenizer property

keras_hub.models.Qwen3CausalLMPreprocessor.tokenizer

The tokenizer used to tokenize strings.