public float getSegmentProximity() {
        if (matches == 0) return 0;
        return 1 - segmentDistance / source.getField().terms().size();
    }
Returns the closeness of the segments in the field: <code>1-segmentDistance/fieldLength</code>
searchlib/src/main/java/com/yahoo/searchlib/ranking/features/fieldmatch/FieldMatchMetrics.java