BertMaskedLM model

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BertMaskedLM class

keras_nlp.models.BertMaskedLM(backbone, preprocessor=None, **kwargs)

An end-to-end BERT model for the masked language modeling task.

This model will train BERT on a masked language modeling task. The model will predict labels for a number of masked tokens in the input data. For usage of this model with pre-trained weights, see the from_preset() constructor.

This model can optionally be configured with a preprocessor layer, in which case inputs can be raw string features during fit(), predict(), and evaluate(). Inputs will be tokenized and dynamically masked during training and evaluation. This is done by default when creating the model with from_preset().

Disclaimer: Pre-trained models are provided on an "as is" basis, without warranties or conditions of any kind.

Arguments

• backbone: A keras_nlp.models.BertBackbone instance.
• preprocessor: A keras_nlp.models.BertMaskedLMPreprocessor or None. If None, this model will not apply preprocessing, and inputs should be preprocessed before calling the model.

Examples

Raw string data.

features = ["The quick brown fox jumped.", "I forgot my homework."]

# Pretrained language model.
masked_lm = keras_nlp.models.BertMaskedLM.from_preset(
    "bert_base_en_uncased",
)
masked_lm.fit(x=features, batch_size=2)

# Re-compile (e.g., with a new learning rate).
masked_lm.compile(
    loss=keras.losses.SparseCategoricalCrossentropy(from_logits=True),
    optimizer=keras.optimizers.Adam(5e-5),
    jit_compile=True,
)
# Access backbone programmatically (e.g., to change `trainable`).
masked_lm.backbone.trainable = False
# Fit again.
masked_lm.fit(x=features, batch_size=2)

Preprocessed integer data.

# Create preprocessed batch where 0 is the mask token.
features = {
    "token_ids": np.array([[1, 2, 0, 4, 0, 6, 7, 8]] * 2),
    "padding_mask": np.array([[1, 1, 1, 1, 1, 1, 1, 1]] * 2),
    "mask_positions": np.array([[2, 4]] * 2),
    "segment_ids": np.array([[0, 0, 0, 0, 0, 0, 0, 0]] * 2)
}
# Labels are the original masked values.
labels = [[3, 5]] * 2

masked_lm = keras_nlp.models.BertMaskedLM.from_preset(
    "bert_base_en_uncased",
    preprocessor=None,
)
masked_lm.fit(x=features, y=labels, batch_size=2)

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from_preset method

BertMaskedLM.from_preset(preset, load_weights=True, **kwargs)

Instantiate a keras_nlp.models.Task 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 a 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 Task 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 a task specific base class like keras_nlp.models.CausalLM.from_preset(), or from a model class like keras_nlp.models.BertClassifier.from_preset(). If calling from the a 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 Gemma generative task.
causal_lm = keras_nlp.models.CausalLM.from_preset(
    "gemma_2b_en",
)

# Load a Bert classification task.
model = keras_nlp.models.Classifier.from_preset(
    "bert_base_en",
    num_classes=2,
)

backbone property

keras_nlp.models.BertMaskedLM.backbone

A keras_nlp.models.Backbone model with the core architecture.

preprocessor property

keras_nlp.models.BertMaskedLM.preprocessor

A keras_nlp.models.Preprocessor layer used to preprocess input.