Fields

From LemurWiki

Field operators are defined by using the .field operator when suffixed on a term or other operator.

[edit] Field Restriction and Evaluation

Indri Field Restriction and Evaluation

name	example	behavior
restriction	dog.title	counts only occurrences of dog in title field
	dog.title,header	counts occurrences of dog in title or header
evaluation	dog.(title)	builds belief b(dog) using "title" language model
	dog.(title,header)	b(dog) estimated using language model from concatenation of all title and header fields
#od1(trevor strohman).person(title)		builds a model from all title text for b(#od1(trevor strohman).person) - only counts "trevor strohman" occurrences in person fields

[edit] Passage Retrieval

You can also use the fields for retrieval of passages within the corpus.

Indri Passage Retrieval using Fields

name	example	behavior
field retrieval	#combine[title]( query )	return only title fields ranked according to #combine(query) beliefs are estimated on each title’s language model may use any belief node
passage retrieval	#combine[passage200:100]( query )	dynamically created passages of length 200 created every 100 words are ranked by #combine(query)
	#combine[section]( bootstrap #combine[./title]( methodology ))	Rank sections matching bootstrap where the section’s title also matches methodology. Note that you can use .//field for ancestor and .\field for parent.