from typing import Iterator, Sequence, Iterable, Optional, Dict, Callable, List from thinc.api import Model, set_dropout_rate, Optimizer, Config from itertools import islice from .pipe import Pipe from ..training import Example, validate_examples from ..tokens import Doc from ..vocab import Vocab from ..language import Language from ..errors import Errors from ..util import minibatch default_model_config = """ [model] @architectures = "spacy.HashEmbedCNN.v1" pretrained_vectors = null width = 96 depth = 4 embed_size = 2000 window_size = 1 maxout_pieces = 3 subword_features = true """ DEFAULT_TOK2VEC_MODEL = Config().from_str(default_model_config)["model"] @Language.factory( "tok2vec", assigns=["doc.tensor"], default_config={"model": DEFAULT_TOK2VEC_MODEL} ) def make_tok2vec(nlp: Language, name: str, model: Model) -> "Tok2Vec": return Tok2Vec(nlp.vocab, model, name) class Tok2Vec(Pipe): """Apply a "token-to-vector" model and set its outputs in the doc.tensor attribute. This is mostly useful to share a single subnetwork between multiple components, e.g. to have one embedding and CNN network shared between a parser, tagger and NER. In order to use the `Tok2Vec` predictions, subsequent components should use the `Tok2VecListener` layer as the tok2vec subnetwork of their model. This layer will read data from the `doc.tensor` attribute during prediction. During training, the `Tok2Vec` component will save its prediction and backprop callback for each batch, so that the subsequent components can backpropagate to the shared weights. This implementation is used because it allows us to avoid relying on object identity within the models to achieve the parameter sharing. """ def __init__(self, vocab: Vocab, model: Model, name: str = "tok2vec") -> None: """Initialize a tok2vec component. vocab (Vocab): The shared vocabulary. model (thinc.api.Model[List[Doc], List[Floats2d]]): The Thinc Model powering the pipeline component. It should take a list of Doc objects as input, and output a list of 2d float arrays. name (str): The component instance name. DOCS: https://nightly.spacy.io/api/tok2vec#init """ self.vocab = vocab self.model = model self.name = name self.listeners = [] self.cfg = {} def add_listener(self, listener: "Tok2VecListener") -> None: """Add a listener for a downstream component. Usually internals.""" self.listeners.append(listener) def find_listeners(self, model: Model) -> None: """Walk over a model, looking for layers that are Tok2vecListener subclasses that have an upstream_name that matches this component. Listeners can also set their upstream_name attribute to the wildcard string '*' to match any `Tok2Vec`. You're unlikely to ever need multiple `Tok2Vec` components, so it's fine to leave your listeners upstream_name on '*'. """ for node in model.walk(): if isinstance(node, Tok2VecListener) and node.upstream_name in ( "*", self.name, ): self.add_listener(node) def __call__(self, doc: Doc) -> Doc: """Add context-sensitive embeddings to the Doc.tensor attribute, allowing them to be used as features by downstream components. docs (Doc): The Doc to process. RETURNS (Doc): The processed Doc. DOCS: https://nightly.spacy.io/api/tok2vec#call """ tokvecses = self.predict([doc]) self.set_annotations([doc], tokvecses) return doc def pipe(self, stream: Iterator[Doc], *, batch_size: int = 128) -> Iterator[Doc]: """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 components are applied to the Doc. stream (Iterable[Doc]): A stream of documents. batch_size (int): The number of documents to buffer. YIELDS (Doc): Processed documents in order. DOCS: https://nightly.spacy.io/api/tok2vec#pipe """ for docs in minibatch(stream, batch_size): docs = list(docs) tokvecses = self.predict(docs) self.set_annotations(docs, tokvecses) yield from docs def predict(self, docs: Iterable[Doc]): """Apply the pipeline's model to a batch of docs, without modifying them. Returns a single tensor for a batch of documents. docs (Iterable[Doc]): The documents to predict. RETURNS: Vector representations for each token in the documents. DOCS: https://nightly.spacy.io/api/tok2vec#predict """ tokvecs = self.model.predict(docs) batch_id = Tok2VecListener.get_batch_id(docs) for listener in self.listeners: listener.receive(batch_id, tokvecs, lambda dX: []) return tokvecs def set_annotations(self, docs: Sequence[Doc], tokvecses) -> None: """Modify a batch of documents, using pre-computed scores. docs (Iterable[Doc]): The documents to modify. tokvecses: The tensors to set, produced by Tok2Vec.predict. DOCS: https://nightly.spacy.io/api/tok2vec#set_annotations """ for doc, tokvecs in zip(docs, tokvecses): assert tokvecs.shape[0] == len(doc) doc.tensor = tokvecs def update( self, examples: Iterable[Example], *, drop: float = 0.0, sgd: Optional[Optimizer] = None, losses: Optional[Dict[str, float]] = None, set_annotations: bool = False, ): """Learn from a batch of documents and gold-standard information, updating the pipe's model. examples (Iterable[Example]): A batch of Example objects. drop (float): The dropout rate. set_annotations (bool): Whether or not to update the Example objects with the predictions. sgd (thinc.api.Optimizer): The optimizer. losses (Dict[str, float]): Optional record of the loss during training. Updated using the component name as the key. RETURNS (Dict[str, float]): The updated losses dictionary. DOCS: https://nightly.spacy.io/api/tok2vec#update """ if losses is None: losses = {} validate_examples(examples, "Tok2Vec.update") docs = [eg.predicted for eg in examples] set_dropout_rate(self.model, drop) tokvecs, bp_tokvecs = self.model.begin_update(docs) d_tokvecs = [self.model.ops.alloc2f(*t2v.shape) for t2v in tokvecs] losses.setdefault(self.name, 0.0) def accumulate_gradient(one_d_tokvecs): """Accumulate tok2vec loss and gradient. This is passed as a callback to all but the last listener. Only the last one does the backprop. """ nonlocal d_tokvecs for i in range(len(one_d_tokvecs)): d_tokvecs[i] += one_d_tokvecs[i] losses[self.name] += float((one_d_tokvecs[i] ** 2).sum()) def backprop(one_d_tokvecs): """Callback to actually do the backprop. Passed to last listener.""" accumulate_gradient(one_d_tokvecs) d_docs = bp_tokvecs(d_tokvecs) if sgd is not None: self.model.finish_update(sgd) return d_docs batch_id = Tok2VecListener.get_batch_id(docs) for listener in self.listeners[:-1]: listener.receive(batch_id, tokvecs, accumulate_gradient) if self.listeners: self.listeners[-1].receive(batch_id, tokvecs, backprop) if set_annotations: self.set_annotations(docs, tokvecs) return losses def get_loss(self, examples, scores) -> None: pass def initialize( self, get_examples: Callable[[], Iterable[Example]], *, nlp: Optional[Language] = None, ): """Initialize the pipe for training, using a representative set of data examples. get_examples (Callable[[], Iterable[Example]]): Function that returns a representative sample of gold-standard Example objects. nlp (Language): The current nlp object the component is part of. DOCS: https://nightly.spacy.io/api/tok2vec#initialize """ self._ensure_examples(get_examples) doc_sample = [] for example in islice(get_examples(), 10): doc_sample.append(example.x) assert doc_sample, Errors.E923.format(name=self.name) self.model.initialize(X=doc_sample) def add_label(self, label): raise NotImplementedError class Tok2VecListener(Model): """A layer that gets fed its answers from an upstream connection, for instance from a component earlier in the pipeline. The Tok2VecListener layer is used as a sublayer within a component such as a parser, NER or text categorizer. Usually you'll have multiple listeners connecting to a single upstream Tok2Vec component, that's earlier in the pipeline. The Tok2VecListener layers act as proxies, passing the predictions from the Tok2Vec component into downstream components, and communicating gradients back upstream. """ name = "tok2vec-listener" def __init__(self, upstream_name: str, width: int) -> None: """ upstream_name (str): A string to identify the 'upstream' Tok2Vec component to communicate with. The upstream name should either be the wildcard string '*', or the name of the `Tok2Vec` component. You'll almost never have multiple upstream Tok2Vec components, so the wildcard string will almost always be fine. width (int): The width of the vectors produced by the upstream tok2vec component. """ Model.__init__(self, name=self.name, forward=forward, dims={"nO": width}) self.upstream_name = upstream_name self._batch_id = None self._outputs = None self._backprop = None @classmethod def get_batch_id(cls, inputs: List[Doc]) -> int: """Calculate a content-sensitive hash of the batch of documents, to check whether the next batch of documents is unexpected. """ return sum(sum(token.orth for token in doc) for doc in inputs) def receive(self, batch_id: int, outputs, backprop) -> None: """Store a batch of training predictions and a backprop callback. The predictions and callback are produced by the upstream Tok2Vec component, and later will be used when the listener's component's model is called. """ self._batch_id = batch_id self._outputs = outputs self._backprop = backprop def verify_inputs(self, inputs) -> bool: """Check that the batch of Doc objects matches the ones we have a prediction for. """ if self._batch_id is None and self._outputs is None: raise ValueError(Errors.E954) else: batch_id = self.get_batch_id(inputs) if batch_id != self._batch_id: raise ValueError(Errors.E953.format(id1=batch_id, id2=self._batch_id)) else: return True def forward(model: Tok2VecListener, inputs, is_train: bool): """Supply the outputs from the upstream Tok2Vec component.""" if is_train: model.verify_inputs(inputs) return model._outputs, model._backprop else: # This is pretty grim, but it's hard to do better :(. # It's hard to avoid relying on the doc.tensor attribute, because the # pipeline components can batch the data differently during prediction. # That doesn't happen in update, where the nlp object works on batches # of data. # When the components batch differently, we don't receive a matching # prediction from the upstream, so we can't predict. if not all(doc.tensor.size for doc in inputs): # But we do need to do *something* if the tensor hasn't been set. # The compromise is to at least return data of the right shape, # so the output is valid. width = model.get_dim("nO") outputs = [model.ops.alloc2f(len(doc), width) for doc in inputs] else: outputs = [doc.tensor for doc in inputs] return outputs, lambda dX: []