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Spelling API

Functions and classes for correcting typos in user queries using edit-distance (Damerau-Levenshtein) matching against the terms in the index.

Corrector Objects​

Corrector​

class whoosh.spelling.Corrector

Base class for spelling correction objects. Concrete subclasses implement the _suggestions() method.

Methods:

suggest(text, limit=5, maxdist=2, prefix=0)​

Returns a list of suggested corrections for text, ranked by edit distance then by frequency.

  • text: The text to check. Will not be added to suggestions even if it appears in the index.
  • limit: Maximum number of suggestions to return.
  • maxdist: Maximum edit distance to look at (values > 2 are inefficient).
  • prefix: Require suggestions to share this length of prefix with text. Increasing to even 1 dramatically speeds up suggestions.

_suggestions(text, maxdist, prefix)​

Low-level method yielding (score, suggestion) tuples. Subclasses must implement this.

ReaderCorrector​

class whoosh.spelling.ReaderCorrector(reader, fieldname, fieldobj)

Suggests corrections based on terms in a specific field of an IndexReader.

Ranks suggestions by edit distance, then by highest to lowest frequency.

Constructor:

  • reader: An IndexReader object.
  • fieldname: The name of the field to get suggestions from.
  • fieldobj: The FieldType for the field.

ListCorrector​

class whoosh.spelling.ListCorrector(wordlist)

Suggests corrections based on a sorted list of strings.

Constructor:

  • wordlist: A sorted list of words to match against.

MultiCorrector​

class whoosh.spelling.MultiCorrector(correctors, op)

Merges suggestions from a list of sub-correctors.

Constructor:

  • correctors: List of Corrector objects.
  • op: A function (e.g., max or operator.add) to combine scores from multiple correctors for the same suggestion.

Query Correction​

Correction​

class whoosh.spelling.Correction(q, qstring, corr_q, tokens)

Represents the corrected version of a user query string.

Attributes:

  • query: The corrected Query object.
  • string: The corrected user query string.
  • original_query: The original Query object.
  • original_string: The original user query string.
  • tokens: List of token objects representing corrected words.

Methods:

format_string(formatter)​

Highlights corrected words in the original query string using the given Formatter.

from whoosh import highlight

correction = searcher.correct_query(q, qstring)
hf = highlight.HtmlFormatter(classname="change")
html = correction.format_string(hf)
  • formatter: A Formatter instance (or class, which will be instantiated).
  • Returns: Formatted string, typically with corrections emphasized.

QueryCorrector​

class whoosh.spelling.QueryCorrector(fieldname)

Base class for objects that correct words in a user query.

Constructor:

  • fieldname: The default field name for corrections.

Methods:

correct_query(q, qstring)​

Returns a Correction object representing the corrected form of the given query.

  • q: The original Query tree to be corrected.
  • qstring: The original user query string (may be None).
  • Returns: A Correction object.

field()​

Returns the field name this corrector operates on.

SimpleQueryCorrector​

class whoosh.spelling.SimpleQueryCorrector(
    correctors: dict,
    terms: list,
    aliases=None,
    prefix: int = 0,
    maxdist: int = 2
)

A simple query corrector based on a mapping of field names to Corrector objects, and a list of (fieldname, text) tuples to correct.

Constructor:

  • correctors: Dictionary mapping field names to Corrector objects.
  • terms: Sequence of (fieldname, text) tuples representing terms to be corrected.
  • aliases: Dictionary mapping field names in the query to field names for spelling suggestions.
  • prefix: Suggested replacement words must share this number of initial characters. Default 0.
  • maxdist: Maximum edit distance for suggestions. Values > 2 may be slow.