tfm.nlp.models.BertClassifier

Classifier model based on a BERT-style transformer-based encoder.

tfm.nlp.models.BertClassifier(
    network,
    num_classes,
    initializer='glorot_uniform',
    dropout_rate=0.1,
    use_encoder_pooler=True,
    head_name='sentence_prediction',
    cls_head=None,
    **kwargs
)

This is an implementation of the network structure surrounding a transformer encoder as described in "BERT: Pre-training of Deep Bidirectional Transformers for Language Understanding" (https://arxiv.org/abs/1810.04805).

The BertClassifier allows a user to pass in a transformer stack, and instantiates a classification network based on the passed num_classes argument. If num_classes is set to 1, a regression network is instantiated.

network A transformer network. This network should output a sequence output and a classification output. Furthermore, it should expose its embedding table via a "get_embedding_table" method.
num_classes Number of classes to predict from the classification network.
initializer The initializer (if any) to use in the classification networks. Defaults to a Glorot uniform initializer.
dropout_rate The dropout probability of the cls head.
use_encoder_pooler Whether to use the pooler layer pre-defined inside the encoder.
head_name Name of the classification head.
cls_head (Optional) The layer instance to use for the classifier head. It should take in the output from network and produce the final logits. If set, the arguments ('num_classes', 'initializer', 'dropout_rate', 'use_encoder_pooler', 'head_name') will be ignored.

checkpoint_items

Methods

call

call(
    inputs, training=None, mask=None
)

Calls the model on new inputs and returns the outputs as tensors.

In this case call() just reapplies all ops in the graph to the new inputs (e.g. build a new computational graph from the provided inputs).

Args
inputs Input tensor, or dict/list/tuple of input tensors.
training Boolean or boolean scalar tensor, indicating whether to run the Network in training mode or inference mode.
mask A mask or list of masks. A mask can be either a boolean tensor or None (no mask). For more details, check the guide here.

Returns
A tensor if there is a single output, or a list of tensors if there are more than one outputs.