A binary classifier is used to say whether or not a page has a property (for example, being a spam page or not). Classifiers can be created using the Manage Classifiers activity.

The classifiers that have been created in this Yioop instance are listed in the table below and can be used for future crawls. Given a classifier named foo, selecting the Use to Classify check box for it tells Yioop to insert some subset of the following labels as meta-words when it indexes a page:

 class:foo
 class:foo:10plus
 class:foo:20plus
 class:foo:30plus
 class:foo:40plus
 ...
 class:foo:50
 ...

When a document is scored against a classifier foo, it gets a score between 0 and 1 and if the score is greater than 0.5 the meta-word class:foo is added. A meta-word class:foo:XXplus indicates the document achieved at least a score of XX with respect to the classifier, and a meta-word class:foo:XX indicates it had a score between 0.XX and 0.XX + 0.9.

The Use to Rank checkbox indicates that Yioop should take the score between 0 and 1 and use this as one of the scores when ranking search results.