@ Override public void addPreference ( final U u , final I i , final Double d ) { // update direct map Map < I , Double > userPreferences = userItemPreferences . get ( u ) ; if ( userPreferences == null ) { userPreferences = new HashMap <> ( ) ; userItemPreferences . put ( u , userPreferences ) ; } Double preference = userPreferences . get ( i ) ; if ( preference == null ) { preference = 0.0 ; } else if ( ignoreDuplicatePreferences ) { // if duplicate preferences should be ignored, then we do not take into account the new value preference = null ; } if ( preference != null ) { preference += d ; userPreferences . put ( i , preference ) ; } // update items items . add ( i ) ; }
Method that adds a preference to the model between a user and an item .