SpanCategorizer
A span categorizer consists of two parts: a suggester function that proposes candidate spans, which may or may not overlap, and a labeler model that predicts zero or more labels for each candidate.
This component comes in two forms: spancat
and spancat_singlelabel
(added in
spaCy v3.5.1). When you need to perform multi-label classification on your
spans, use spancat
. The spancat
component uses a Logistic
layer where the
output class probabilities are independent for each class. However, if you need
to predict at most one true class for a span, then use spancat_singlelabel
. It
uses a Softmax
layer and treats the task as a multi-class problem.
Predicted spans will be saved in a SpanGroup
on the doc
under doc.spans[spans_key]
, where spans_key
is a component config setting.
Individual span scores are stored in doc.spans[spans_key].attrs["scores"]
.
Assigned Attributes
Predictions will be saved to Doc.spans[spans_key]
as a
SpanGroup
. The scores for the spans in the SpanGroup
will
be saved in SpanGroup.attrs["scores"]
.
spans_key
defaults to "sc"
, but can be passed as a parameter. The spancat
component will overwrite any existing spans under the spans key
doc.spans[spans_key]
.
Location | Value |
---|---|
Doc.spans[spans_key] | The annotated spans. SpanGroup |
Doc.spans[spans_key].attrs["scores"] | The score for each span in the SpanGroup . Floats1d |
Config and implementation
The default config is defined by the pipeline component factory and describes
how the component should be configured. You can override its settings via the
config
argument on nlp.add_pipe
or in your
config.cfg
for training. See the
model architectures documentation for details on the
architectures and their arguments and hyperparameters.
Setting | Description |
---|---|
suggester | A function that suggests spans. Spans are returned as a ragged array with two integer columns, for the start and end positions. Defaults to ngram_suggester . Callable[[Iterable[Doc], Optional[Ops]],Ragged] |
model | A model instance that is given a a list of documents and (start, end) indices representing candidate span offsets. The model predicts a probability for each category for each span. Defaults to SpanCategorizer. Model[Tuple[List[Doc],Ragged],Floats2d] |
spans_key | Key of the Doc.spans dict to save the spans under. During initialization and training, the component will look for spans on the reference document under the same key. Defaults to "sc" . str |
threshold | Minimum probability to consider a prediction positive. Spans with a positive prediction will be saved on the Doc. Meant to be used in combination with the multi-class spancat component with a Logistic scoring layer. Defaults to 0.5 . float |
max_positive | Maximum number of labels to consider positive per span. Defaults to None , indicating no limit. Meant to be used together with the spancat component and defaults to 0 with spancat_singlelabel . Optional[int] |
scorer | The scoring method. Defaults to Scorer.score_spans for Doc.spans[spans_key] with overlapping spans allowed. Optional[Callable] |
add_negative_label v3.5.1 | Whether to learn to predict a special negative label for each unannotated Span . This should be True when using a Softmax classifier layer and so its True by default for spancat_singlelabel . Spans with negative labels and their scores are not stored as annotations. bool |
negative_weight v3.5.1 | Multiplier for the loss terms. It can be used to downweight the negative samples if there are too many. It is only used when add_negative_label is True . Defaults to 1.0 . float |
allow_overlap v3.5.1 | If True , the data is assumed to contain overlapping spans. It is only available when max_positive is exactly 1. Defaults to True . bool |
explosion/spaCy/master/spacy/pipeline/spancat.py
SpanCategorizer.__init__ method
Create a new pipeline instance. In your application, you would normally use a
shortcut for this and instantiate the component using its string name and
nlp.add_pipe
.
Name | Description |
---|---|
vocab | The shared vocabulary. Vocab |
model | A model instance that is given a a list of documents and (start, end) indices representing candidate span offsets. The model predicts a probability for each category for each span. Model[Tuple[List[Doc],Ragged],Floats2d] |
suggester | A function that suggests spans. Spans are returned as a ragged array with two integer columns, for the start and end positions. Callable[[Iterable[Doc], Optional[Ops]],Ragged] |
name | String name of the component instance. Used to add entries to the losses during training. str |
keyword-only | |
spans_key | Key of the Doc.spans dict to save the spans under. During initialization and training, the component will look for spans on the reference document under the same key. Defaults to "sc" . str |
threshold | Minimum probability to consider a prediction positive. Spans with a positive prediction will be saved on the Doc. Defaults to 0.5 . float |
max_positive | Maximum number of labels to consider positive per span. Defaults to None , indicating no limit. Optional[int] |
allow_overlap v3.5.1 | If True , the data is assumed to contain overlapping spans. It is only available when max_positive is exactly 1. Defaults to True . bool |
add_negative_label v3.5.1 | Whether to learn to predict a special negative label for each unannotated Span . This should be True when using a Softmax classifier layer and so its True by default for spancat_singlelabel . Spans with negative labels and their scores are not stored as annotations. bool |
negative_weight v3.5.1 | Multiplier for the loss terms. It can be used to downweight the negative samples if there are too many . It is only used when add_negative_label is True . Defaults to 1.0 . float |
SpanCategorizer.__call__ method
Apply the pipe to one document. The document is modified in place, and returned.
This usually happens under the hood when the nlp
object is called on a text
and all pipeline components are applied to the Doc
in order. Both
__call__
and pipe
delegate to the predict
and
set_annotations
methods.
Name | Description |
---|---|
doc | The document to process. Doc |
RETURNS | The processed document. Doc |
SpanCategorizer.pipe method
Apply the pipe to a stream of documents. This usually happens under the hood
when the nlp
object is called on a text and all pipeline components are
applied to the Doc
in order. Both __call__
and
pipe
delegate to the
predict
and
set_annotations
methods.
Name | Description |
---|---|
stream | A stream of documents. Iterable[Doc] |
keyword-only | |
batch_size | The number of documents to buffer. Defaults to 128 . int |
YIELDS | The processed documents in order. Doc |
SpanCategorizer.initialize method
Initialize the component for training. get_examples
should be a function that
returns an iterable of Example
objects. At least one example
should be supplied. The data examples are used to initialize the model of
the component and can either be the full training data or a representative
sample. Initialization includes validating the network,
inferring missing shapes and
setting up the label scheme based on the data. This method is typically called
by Language.initialize
and lets you customize
arguments it receives via the
[initialize.components]
block in the
config.
Name | Description |
---|---|
get_examples | Function that returns gold-standard annotations in the form of Example objects. Must contain at least one Example . Callable[[], Iterable[Example]] |
keyword-only | |
nlp | The current nlp object. Defaults to None . Optional[Language] |
labels | The label information to add to the component, as provided by the label_data property after initialization. To generate a reusable JSON file from your data, you should run the init labels command. If no labels are provided, the get_examples callback is used to extract the labels from the data, which may be a lot slower. Optional[Iterable[str]] |
SpanCategorizer.predict method
Apply the component’s model to a batch of Doc
objects without
modifying them.
Name | Description |
---|---|
docs | The documents to predict. Iterable[Doc] |
RETURNS | The model’s prediction for each document. |
SpanCategorizer.set_annotations method
Modify a batch of Doc
objects using pre-computed scores.
Name | Description |
---|---|
docs | The documents to modify. Iterable[Doc] |
scores | The scores to set, produced by SpanCategorizer.predict . |
SpanCategorizer.update method
Learn from a batch of Example
objects containing the
predictions and gold-standard annotations, and update the component’s model.
Delegates to predict
and
get_loss
.
Name | Description |
---|---|
examples | A batch of Example objects to learn from. Iterable[Example] |
keyword-only | |
drop | The dropout rate. float |
sgd | An optimizer. Will be created via create_optimizer if not set. Optional[Optimizer] |
losses | Optional record of the loss during training. Updated using the component name as the key. Optional[Dict[str, float]] |
RETURNS | The updated losses dictionary. Dict[str, float] |
SpanCategorizer.set_candidates methodv3.3
Use the suggester to add a list of Span
candidates to a list of
Doc
objects. This method is intended to be used for debugging
purposes.
Name | Description |
---|---|
docs | The documents to modify. Iterable[Doc] |
candidates_key | Key of the Doc.spans dict to save the candidate spans under. str |
SpanCategorizer.get_loss method
Find the loss and gradient of loss for the batch of documents and their predicted scores.
Name | Description |
---|---|
examples | The batch of examples. Iterable[Example] |
spans_scores | Scores representing the model’s predictions. Tuple[Ragged,Floats2d] |
RETURNS | The loss and the gradient, i.e. (loss, gradient) . Tuple[float, float] |
SpanCategorizer.create_optimizer method
Create an optimizer for the pipeline component.
Name | Description |
---|---|
RETURNS | The optimizer. Optimizer |
SpanCategorizer.use_params methodcontextmanager
Modify the pipe’s model to use the given parameter values.
Name | Description |
---|---|
params | The parameter values to use in the model. dict |
SpanCategorizer.add_label method
Add a new label to the pipe. Raises an error if the output dimension is already
set, or if the model has already been fully initialized. Note
that you don’t have to call this method if you provide a representative data
sample to the initialize
method. In this case, all labels
found in the sample will be automatically added to the model, and the output
dimension will be inferred
automatically.
Name | Description |
---|---|
label | The label to add. str |
RETURNS | 0 if the label is already present, otherwise 1 . int |
SpanCategorizer.to_disk method
Serialize the pipe to disk.
Name | Description |
---|---|
path | A path to a directory, which will be created if it doesn’t exist. Paths may be either strings or Path -like objects. Union[str,Path] |
keyword-only | |
exclude | String names of serialization fields to exclude. Iterable[str] |
SpanCategorizer.from_disk method
Load the pipe from disk. Modifies the object in place and returns it.
Name | Description |
---|---|
path | A path to a directory. Paths may be either strings or Path -like objects. Union[str,Path] |
keyword-only | |
exclude | String names of serialization fields to exclude. Iterable[str] |
RETURNS | The modified SpanCategorizer object. SpanCategorizer |
SpanCategorizer.to_bytes method
Serialize the pipe to a bytestring.
Name | Description |
---|---|
keyword-only | |
exclude | String names of serialization fields to exclude. Iterable[str] |
RETURNS | The serialized form of the SpanCategorizer object. bytes |
SpanCategorizer.from_bytes method
Load the pipe from a bytestring. Modifies the object in place and returns it.
Name | Description |
---|---|
bytes_data | The data to load from. bytes |
keyword-only | |
exclude | String names of serialization fields to exclude. Iterable[str] |
RETURNS | The SpanCategorizer object. SpanCategorizer |
SpanCategorizer.labels property
The labels currently added to the component.
Name | Description |
---|---|
RETURNS | The labels added to the component. Tuple[str, …] |
SpanCategorizer.label_data property
The labels currently added to the component and their internal meta information.
This is the data generated by init labels
and used by
SpanCategorizer.initialize
to initialize
the model with a pre-defined label set.
Name | Description |
---|---|
RETURNS | The label data added to the component. Tuple[str, …] |
Serialization fields
During serialization, spaCy will export several data fields used to restore
different aspects of the object. If needed, you can exclude them from
serialization by passing in the string names via the exclude
argument.
Name | Description |
---|---|
vocab | The shared Vocab . |
cfg | The config file. You usually don’t want to exclude this. |
model | The binary model data. You usually don’t want to exclude this. |
Suggesters registered functions
spacy.ngram_suggester.v1
Suggest all spans of the given lengths. Spans are returned as a ragged array of integers. The array has two columns, indicating the start and end position.
Name | Description |
---|---|
sizes | The phrase lengths to suggest. For example, [1, 2] will suggest phrases consisting of 1 or 2 tokens. List[int] |
CREATES | The suggester function. Callable[[Iterable[Doc], Optional[Ops]],Ragged] |
spacy.ngram_range_suggester.v1
Suggest all spans of at least length min_size
and at most length max_size
(both inclusive). Spans are returned as a ragged array of integers. The array
has two columns, indicating the start and end position.
Name | Description |
---|---|
min_size | The minimal phrase lengths to suggest (inclusive). [int] |
max_size | The maximal phrase lengths to suggest (inclusive). [int] |
CREATES | The suggester function. Callable[[Iterable[Doc], Optional[Ops]],Ragged] |
spacy.preset_spans_suggester.v1
Suggest all spans that are already stored in doc.spans[spans_key]. This is
useful when an upstream component is used to set the spans on the Doc such as a
SpanRuler
or SpanFinder
.
Name | Description |
---|---|
spans_key | Key of Doc.spans that provides spans to suggest. str |
CREATES | The suggester function. Callable[[Iterable[Doc], Optional[Ops]],Ragged] |