Customizing the NLP engine in Presidio Analyzer

Presidio uses NLP engines for two main tasks: NER based PII identification, and feature extraction for downstream rule based logic (such as leveraging context words for improved detection). While Presidio comes with an open-source model (the en_core_web_lg model from spaCy), additional NLP models and frameworks could be plugged in, either public or proprietary. These models can be trained or downloaded from existing NLP frameworks like spaCy, Stanza and transformers.

In addition, other types of NLP frameworks can be integrated into Presidio.

Setting up a custom NLP model

• spaCy or stanza
• transformers

Configure Presidio to use the new model

Configuration can be done in two ways:

• Via code: Create an NlpEngine using the NlpEnginerProvider class, and pass it to the AnalyzerEngine as input:

  from presidio_analyzer import AnalyzerEngine, RecognizerRegistry
  from presidio_analyzer.nlp_engine import NlpEngineProvider
  
  # Create configuration containing engine name and models
  configuration = {
      "nlp_engine_name": "spacy",
      "models": [{"lang_code": "es", "model_name": "es_core_news_md"},
                  {"lang_code": "en", "model_name": "en_core_web_lg"}],
  }
  
  # Create NLP engine based on configuration
  provider = NlpEngineProvider(nlp_configuration=configuration)
  nlp_engine_with_spanish = provider.create_engine()
  
  # Pass the created NLP engine and supported_languages to the AnalyzerEngine
  analyzer = AnalyzerEngine(
      nlp_engine=nlp_engine_with_spanish, 
      supported_languages=["en", "es"]
  )
  
  # Analyze in different languages
  results_spanish = analyzer.analyze(text="Mi nombre es Morris", language="es")
  print(results_spanish)
  
  results_english = analyzer.analyze(text="My name is Morris", language="en")
  print(results_english)

• Via configuration: Set up the models which should be used in the default conf file.

  An example Conf file:

  nlp_engine_name: spacy
  models:
      -
      lang_code: en
      model_name: en_core_web_lg
      -
      lang_code: es
      model_name: es_core_news_md 
  ner_model_configuration:
  labels_to_ignore:
  - O
  model_to_presidio_entity_mapping:
      PER: PERSON
      LOC: LOCATION
      ORG: ORGANIZATION
      AGE: AGE
      ID: ID
      DATE: DATE_TIME
  low_confidence_score_multiplier: 0.4
  low_score_entity_names:
  - ID
  - ORG

  The ner_model_configuration section contains the following parameters:

  • labels_to_ignore: A list of labels to ignore. For example, O (no entity) or entities you are not interested in returning.

  • model_to_presidio_entity_mapping: A mapping between the transformers model labels and the Presidio entity types.

  • low_confidence_score_multiplier: A multiplier to apply to the score of entities with low confidence.

  • low_score_entity_names: A list of entity types to apply the low confidence score multiplier to.

    The default conf file is read during the default initialization of the AnalyzerEngine. Alternatively, the path to a custom configuration file can be passed to the NlpEngineProvider:

    from presidio_analyzer import AnalyzerEngine, RecognizerRegistry
    from presidio_analyzer.nlp_engine import NlpEngineProvider
    
    LANGUAGES_CONFIG_FILE = "./docs/analyzer/languages-config.yml"
    
    # Create NLP engine based on configuration file
    provider = NlpEngineProvider(conf_file=LANGUAGES_CONFIG_FILE)
    nlp_engine_with_spanish = provider.create_engine()
    
    # Pass created NLP engine and supported_languages to the AnalyzerEngine
    analyzer = AnalyzerEngine(
        nlp_engine=nlp_engine_with_spanish, 
        supported_languages=["en", "es"]
    )
    
    # Analyze in different languages
    results_spanish = analyzer.analyze(text="Mi nombre es David", language="es")
    print(results_spanish)
    
    results_english = analyzer.analyze(text="My name is David", language="en")
    print(results_english)

    In this examples we: a. create an NlpEngine holding two spaCy models (one in English: en_core_web_lg and one in Spanish: es_core_news_md). b. define the supported_languages parameter accordingly. c. pass requests in each of these languages.

    !!! note "Note" Presidio can currently use one NER model per language via the NlpEngine. If multiple are required, consider wrapping NER models as additional recognizers (see sample here).

Leverage frameworks other than spaCy, Stanza and transformers for ML based PII detection

In addition to the built-in spaCy/Stanza/transformers capabilities, it is possible to create new recognizers which serve as interfaces to other models. For more information:

• Remote recognizer documentation and samples.
• Flair recognizer example

For considerations for creating such recognizers, see the best practices for adding ML recognizers documentation.