//- 💫 DOCS > USAGE > PROCESSING PIPELINES > EXAMPLES

p
    |  To see real-world examples of pipeline factories and components in action,
    |  you can have a look at the source of spaCy's built-in components, e.g.
    |  the #[+api("tagger") #[code Tagger]], #[+api("parser") #[code Parser]] or
    |  #[+api("entityrecognizer") #[code EntityRecongnizer]].

+h(3, "example1") Example: Custom sentence segmentation logic

p
    |  Let's say you want to implement custom logic to improve spaCy's sentence
    |  boundary detection. Currently, sentence segmentation is based on the
    |  dependency parse, which doesn't always produce ideal results. The custom
    |  logic should therefore be applied #[strong after] tokenization, but
    |  #[strong before] the dependency parsing – this way, the parser can also
    |  take advantage of the sentence boundaries.

+code.
    def sbd_component(doc):
        for i, token in enumerate(doc[:-2]):
            # define sentence start if period + titlecase token
            if token.text == '.' and doc[i+1].is_title:
                doc[i+1].sent_start = True
        return doc

p
    |  In this case, we simply want to add the component to the existing
    |  pipeline of the English model. We can do this by inserting it at index 0
    |  of #[code nlp.pipeline]:

+code.
    nlp = spacy.load('en')
    nlp.pipeline.insert(0, sbd_component)

p
    |  When you call #[code nlp] on some text, spaCy will tokenize it to create
    |  a #[code Doc] object, and first call #[code sbd_component] on it, followed
    |  by the model's default pipeline.

+h(3, "example2") Example: Sentiment model

p
    |  Let's say you have trained your own document sentiment model on English
    |  text. After tokenization, you want spaCy to first execute the
    |  #[strong default tensorizer], followed by a custom
    |  #[strong sentiment component] that adds a #[code .sentiment]
    |  property to the #[code Doc], containing your model's sentiment precition.

p
    |  Your component class will have a #[code from_disk()] method that spaCy
    |  calls to load the model data. When called, the component will compute
    |  the sentiment score, add it to the #[code Doc] and return the modified
    |  document. Optionally, the component can include an #[code update()] method
    |  to allow training the model.

+code.
    import pickle
    from pathlib import Path

    class SentimentComponent(object):
        def __init__(self, vocab):
            self.weights = None

        def __call__(self, doc):
            doc.sentiment = sum(self.weights*doc.vector) # set sentiment property
            return doc

        def from_disk(self, path): # path = model path + factory ID ('sentiment')
            self.weights = pickle.load(Path(path) / 'weights.bin') # load weights
            return self

        def update(self, doc, gold): # update weights – allows training!
            prediction = sum(self.weights*doc.vector)
            self.weights -= 0.001*doc.vector*(prediction-gold.sentiment)

p
    |  The factory will initialise the component with the #[code Vocab] object.
    |  To be able to add it to your model's pipeline as #[code 'sentiment'],
    |  it also needs to be registered via
    |  #[+api("spacy#set_factory") #[code set_factory()]].

+code.
    def sentiment_factory(vocab):
        component = SentimentComponent(vocab) # initialise component
        return component

    spacy.set_factory('sentiment', sentiment_factory)

p
    |  The above code should be #[strong shipped with your model]. You can use
    |  the #[+api("cli#package") #[code package]] command to create all required
    |  files and directories. The model package will include an
    |  #[+src(gh("spacy-dev-resources", "templates/model/en_model_name/__init__.py")) #[code __init__.py]]
    |  with a #[code load()] method, that will initialise the language class with
    |  the model's pipeline and call the #[code from_disk()] method to load
    |  the model data.

p
    |  In the model package's meta.json, specify the language class and pipeline
    |  IDs:

+code("meta.json (excerpt)", "json").
    {
        "name": "sentiment_model",
        "lang": "en",
        "version": "1.0.0",
        "spacy_version": ">=2.0.0,<3.0.0",
        "pipeline": ["tensorizer", "sentiment"]
    }

p
    |  When you load your new model, spaCy will call the model's #[code load()]
    |  method. This will return a #[code Language] object with a pipeline
    |  containing the default tensorizer, and the sentiment component returned
    |  by your custom #[code "sentiment"] factory.

+code.
    nlp = spacy.load('en_sentiment_model')
    doc = nlp(u'I love pizza')
    assert doc.sentiment

+infobox("Saving and loading models")
    |  For more information and a detailed guide on how to package your model,
    |  see the documentation on
    |  #[+a("/usage/training#saving-loading") saving and loading models].