Matchers

PhraseMatcher

class
Match sequences of tokens, based on documents

The PhraseMatcher lets you efficiently match large terminology lists. While the Matcher lets you match sequences based on lists of token descriptions, the PhraseMatcher accepts match patterns in the form of Doc objects. See the usage guide for examples.

PhraseMatcher.__init__ method

Create the rule-based PhraseMatcher. Setting a different attr to match on will change the token attributes that will be compared to determine a match. By default, the incoming Doc is checked for sequences of tokens with the same ORTH value, i.e. the verbatim token text. Matching on the attribute LOWER will result in case-insensitive matching, since only the lowercase token texts are compared. In theory, it’s also possible to match on sequences of the same part-of-speech tags or dependency labels.

If validate=True is set, additional validation is performed when pattern are added. At the moment, it will check whether a Doc has attributes assigned that aren’t necessary to produce the matches (for example, part-of-speech tags if the PhraseMatcher matches on the token text). Since this can often lead to significantly worse performance when creating the pattern, a UserWarning will be shown.

NameDescription
vocabThe vocabulary object, which must be shared with the documents the matcher will operate on. Vocab
attr The token attribute to match on. Defaults to ORTH, i.e. the verbatim token text. Union[int, str]
validate Validate patterns added to the matcher. bool

PhraseMatcher.__call__ method

Find all token sequences matching the supplied patterns on the Doc or Span.

NameDescription
doclikeThe Doc or Span to match over. Union[Doc, Span]
keyword-only
as_spans v3.0Instead of tuples, return a list of Span objects of the matches, with the match_id assigned as the span label. Defaults to False. bool

PhraseMatcher.__len__ method

Get the number of rules added to the matcher. Note that this only returns the number of rules (identical with the number of IDs), not the number of individual patterns.

NameDescription

PhraseMatcher.__contains__ method

Check whether the matcher contains rules for a match ID.

NameDescription
keyThe match ID. str

PhraseMatcher.add method

Add a rule to the matcher, consisting of an ID key, one or more patterns, and a callback function to act on the matches. The callback function will receive the arguments matcher, doc, i and matches. If a pattern already exists for the given ID, the patterns will be extended. An on_match callback will be overwritten.

NameDescription
match_idAn ID for the thing you’re matching. str
docsDoc objects of the phrases to match. List[Doc]
keyword-only
on_matchCallback function to act on matches. Takes the arguments matcher, doc, i and matches. Optional[Callable[[Matcher, Doc, int, List[tuple], Any]]

PhraseMatcher.remove method

Remove a rule from the matcher by match ID. A KeyError is raised if the key does not exist.

NameDescription
keyThe ID of the match rule. str