/**
* Computes the difference between two attributes using the given distance metric. This function
* takes care of things like dynamic attributes and null values. This one allows reclamation of a
* difference object.
*
* @param alpha the target attribute
* @param alphaSpan the target attribute's span
* @param beta the candidate attribute
* @param betaSpan the candidate attribute's framespan
* @param blackout the blackout data
* @param blackoutSpan when the blackout is defined
* @param ignore the don't-care data
* @param ignoreSpan the don't-care framespan
* @param frame the frame to compare
* @param cfd information about the media
* @param old cached difference object
* @return the new difference object, or the same one, changed
* @throws IgnoredValueException if the whole of the data on the frame was ignored
*/
public static Measurable.Difference helpGetDiff(
Attribute alpha,
FrameSpan alphaSpan,
Attribute beta,
FrameSpan betaSpan,
Attribute blackout,
FrameSpan blackoutSpan,
Attribute ignore,
FrameSpan ignoreSpan,
int frame,
CanonicalFileDescriptor cfd,
Measurable.Difference old)
throws IgnoredValueException {
if (alpha == null || alpha.getValue(alphaSpan, frame) == null) {
return new Distances.DefaultDifference(
null,
(beta != null) ? beta.getValue(betaSpan, frame) : null,
(blackout != null) ? blackout.getValue(blackoutSpan, frame) : null,
(ignore != null) ? ignore.getValue(ignoreSpan, frame) : null,
cfd);
} else {
Measurable a = alpha.getValue(alphaSpan, frame);
return a.getDifference(
(beta != null) ? beta.getValue(betaSpan, frame) : null,
(blackout != null) ? blackout.getValue(blackoutSpan, frame) : null,
(ignore != null) ? ignore.getValue(ignoreSpan, frame) : null,
cfd,
old);
}
}
/**
* Tests to see if the specified metric name is known for the given attribute data type.
*
* @param type the attribute type
* @param s the name of the distance metric to look for
* @return true if <code>s</code> is the name of a known metric for the type
* @throws UnknownDistanceException if the type is unknown. XXX: shouldn't this be the other way
* around?
*/
public static final boolean isDistanceFor(Measurable type, String s)
throws UnknownDistanceException {
Map<String, Distance> values = distanceMap.get(type.getType());
if (values != null) {
return values.containsKey(s.toLowerCase());
} else {
throw new UnknownDistanceException(type, s);
}
}
/**
* Computes the difference between two attributes using the given distance metric. This must
* operate on the attribute values directly
*
* @param alpha the target attribute
* @param beta the candidate attribute
* @param blackout the blackout data
* @param ignore the don't-care data
* @param cfd information about the media
* @param old cached difference object
* @return the difference
* @throws IgnoredValueException if the whole of the data on the frame was ignored
*/
public static Measurable.Difference helpGetDiff(
Measurable alpha,
Measurable beta,
Measurable blackout,
Measurable ignore,
CanonicalFileDescriptor cfd,
Measurable.Difference old)
throws IgnoredValueException {
if (alpha == null) {
return new Distances.DefaultDifference(null, beta, blackout, ignore, cfd);
} else {
return alpha.getDifference(beta, blackout, ignore, cfd, old);
}
}
/**
* Gets the distance functor for the given type.
*
* @param type the attribute data type
* @param metric the metric name
* @return the metric
* @throws UnknownDistanceException if the metric isn't found
*/
public static final Distance getDistanceFunctor(Measurable type, String metric)
throws UnknownDistanceException {
return Distances.getDistanceFunctor(type.getType(), metric);
}
