/**
* Compare the target segments to the 'otherSegments', and update the classifier by sum_x
* [delta*x], for each example x corresponding to a target segment that's not in otherSegments.
*/
private int compareSegmentsAndIncrement(
ExampleSchema schema,
Segmentation segments,
Segmentation otherSegments,
Hyperplane[] accum,
double delta,
CandidateSegmentGroup g) {
int errors = 0;
// first, work out the name of the previous class for each segment
Map<Segment, String> map = previousClassMap(segments, schema);
Map<Segment, String> otherMap = previousClassMap(otherSegments, schema);
String[] history = new String[1];
for (Iterator<Segment> j = segments.iterator(); j.hasNext(); ) {
Segmentation.Segment seg = j.next();
String previousClass = map.get(seg);
if (seg.lo >= 0
&& (!otherSegments.contains(seg) || !otherMap.get(seg).equals(previousClass))) {
errors++;
history[0] = previousClass;
Instance instance =
new InstanceFromSequence(g.getSubsequenceExample(seg.lo, seg.hi), history);
if (DEBUG)
log.debug(
"class "
+ schema.getClassName(seg.y)
+ " update "
+ delta
+ " for: "
+ instance.getSource());
accum[seg.y].increment(instance, delta);
}
}
return errors;
}
/**
* Build a mapping from segment to string name of previous segment. This should let you look up
* segments which are logically equivalent, as well as ones which are pointer-equivalent (==)
*/
private Map<Segment, String> previousClassMap(Segmentation segments, ExampleSchema schema) {
// use a treemap so that logically equivalent segments be mapped to same previousClass
Map<Segment, String> map = new TreeMap<Segment, String>();
Segmentation.Segment previousSeg = null;
for (Iterator<Segment> j = segments.iterator(); j.hasNext(); ) {
Segmentation.Segment seg = j.next();
String previousClassName =
previousSeg == null ? NULL_CLASS_NAME : schema.getClassName(previousSeg.y);
map.put(seg, previousClassName);
previousSeg = seg;
}
return map;
}
