ComparableMeasurement.java
/* Copyright 2002-2019 CS Systèmes d'Information
* Licensed to CS Systèmes d'Information (CS) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* CS licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.orekit.estimation.measurements;
import org.orekit.time.TimeStamped;
/** Base interface for comparing measurements regardless of their type.
* @author Luc Maisonobe
* @since 9.2
*/
public interface ComparableMeasurement extends TimeStamped, Comparable<ComparableMeasurement> {
/** Get the observed value.
* <p>
* The observed value is the value that was measured by the instrument.
* </p>
* @return observed value
*/
double[] getObservedValue();
/** {@inheritDoc}
* <p>
* Measurements comparison is primarily chronological, but measurements
* with the same date are sorted based on the observed value. Even if they
* have the same value too, they will <em>not</em> be considered equal if they
* correspond to different instances. This allows to store measurements in
* {@link java.util.SortedSet SortedSet} without losing any measurements, even
* redundant ones.
* </p>
*/
@Override
default int compareTo(final ComparableMeasurement other) {
if (this == other) {
// only case where measurements are considered equal
return 0;
}
int result = getDate().compareTo(other.getDate());
if (result == 0) {
// simultaneous measurements, we compare values
final double[] thisV = getObservedValue();
final double[] otherV = other.getObservedValue();
if (thisV.length > otherV.length) {
result = +1;
} else if (thisV.length < otherV.length) {
result = 1;
} else {
for (int i = 0; i < thisV.length && result == 0; ++i) {
result = Double.compare(thisV[i], otherV[i]);
}
if (result == 0) {
// measurements have the same value,
// but we do not want them to appear as equal
// we set up an arbitrary order
result = -1;
}
}
}
return result;
}
}