Package nltk :: Package tag :: Module sequential

Module sequential

Classes for tagging sentences sequentially, left to right. The abstract base class SequentialBackoffTagger serves as the base class for all the taggers in this module. Tagging of individual words is performed by the method choose_tag(), which is defined by subclasses of SequentialBackoffTagger. If a tagger is unable to determine a tag for the specified token, then its backoff tagger is consulted instead. Any SequentialBackoffTagger may serve as a backoff tagger for any other SequentialBackoffTagger.

Classes

[hide private]

Abstract Base Classes

SequentialBackoffTagger
An abstract base class for taggers that tags words sequentially, left to right.

ContextTagger
An abstract base class for sequential backoff taggers that choose a tag for a token based on the value of its "context".

Tagger Classes

DefaultTagger
A tagger that assigns the same tag to every token.

NgramTagger
A tagger that chooses a token's tag based on its word string and on the preceeding n word's tags.

UnigramTagger
A tagger that chooses a token's tag based its word string.

BigramTagger
A tagger that chooses a token's tag based its word string and on the preceeding words' tag.

TrigramTagger
A tagger that chooses a token's tag based its word string and on the preceeding two words' tags.

AffixTagger
A tagger that chooses a token's tag based on a leading or trailing substring of its word string.

RegexpTagger
A tagger that assigns tags to words based on regular expressions over word strings.

ClassifierBasedTagger
A sequential tagger that uses a classifier to choose the tag for each token in a sentence.