dive4elements/river: artifacts/src/main/java/org/dive4elements/river/utils/DoubleUtil.java comparison

Partial fix for flys/1303

author	Sascha L. Teichmann <teichmann@intevation.de>
date	Wed, 26 Jun 2013 13:33:15 +0200
parents	af13ceeba52a
children	eb4ca9a7eaca

comparison

equal deleted inserted replaced

-:2874e16c2cc6
+:898afcce1d0a
 import org.dive4elements.river.artifacts.math.Linear;
 import gnu.trove.TDoubleArrayList;
 import java.util.Arrays;
+import java.util.Comparator;
 import org.apache.log4j.Logger;
 /** Utils to deal with Double precision values. */
 public class DoubleUtil
 {
 /** Private logger. */
 private static Logger log = Logger.getLogger(DoubleUtil.class);
 public static final double DEFAULT_STEP_PRECISION = 1e6;
+public static final Comparator<double []> DOUBLE_PAIR_CMP =
+new Comparator<double []>() {
+@Override
+public int compare(double [] a, double [] b) {
+double diff = a[0] - b[0];
+if (diff < 0d) return -1;
+if (diff > 0d) return +1;
+return 0;
+}
+};
 /** EPSILON for comparison of double precision values. */
 public static final double EPSILON = 1e-4;
 private DoubleUtil() {
 if (d > max) max = d;
 }
 return max;
 }
+/** Sort a and b with a as key. b is ordered accordingly */
+public static final void sortByFirst(double [] a, double [] b) {
+// XXX: Not efficient but bulletproof.
+double [][] pairs = new double[a.length][2];
+for (int i = 0; i < a.length; ++i) {
+double [] p = pairs[i];
+p[0] = a[i];
+p[1] = b[i];
+}
+Arrays.sort(pairs, DOUBLE_PAIR_CMP);
+for (int i = 0; i < a.length; ++i) {
+double [] p = pairs[i];
+a[i] = p[0];
+b[i] = p[1];
+}
+}
 public static void removeNaNs(TDoubleArrayList [] arrays) {
 int dest = 0;
 int A = arrays.length;

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