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Posted to commits@commons.apache.org by oe...@apache.org on 2015/08/22 11:53:36 UTC
[2/2] [math] MATH-990: improved in-place sorting by using a helper
class instead of the generic Pair class,
in order to avoid boxing and unboxing
MATH-990: improved in-place sorting by using a helper class instead of
the generic Pair class, in order to avoid boxing and unboxing
Project: http://git-wip-us.apache.org/repos/asf/commons-math/repo
Commit: http://git-wip-us.apache.org/repos/asf/commons-math/commit/72a46bab
Tree: http://git-wip-us.apache.org/repos/asf/commons-math/tree/72a46bab
Diff: http://git-wip-us.apache.org/repos/asf/commons-math/diff/72a46bab
Branch: refs/heads/master
Commit: 72a46babeb0da02071e47425ebd55da915b98178
Parents: 0b5bd38
Author: Otmar Ertl <ot...@gmail.com>
Authored: Sat Aug 22 11:23:54 2015 +0200
Committer: Otmar Ertl <ot...@gmail.com>
Committed: Sat Aug 22 11:47:09 2015 +0200
----------------------------------------------------------------------
src/changes/changes.xml | 3 ++
.../apache/commons/math4/util/MathArrays.java | 48 ++++++++++++++------
2 files changed, 38 insertions(+), 13 deletions(-)
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http://git-wip-us.apache.org/repos/asf/commons-math/blob/72a46bab/src/changes/changes.xml
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diff --git a/src/changes/changes.xml b/src/changes/changes.xml
index d209db5..afdaa0c 100644
--- a/src/changes/changes.xml
+++ b/src/changes/changes.xml
@@ -54,6 +54,9 @@ If the output is not quite correct, check for invisible trailing spaces!
</release>
<release version="4.0" date="XXXX-XX-XX" description="">
+ <action dev="oertl" type="update" issue="MATH-990">
+ Improved performance of sort-in-place methods by avoiding boxing.
+ </action>
<action dev="erans" type="fix" issue="MATH-1261" due-to="Osamu Ikeuchi"> <!-- backported to 3.6 -->
Avoid overflow in "Fraction" (multiplication or division by an int).
</action>
http://git-wip-us.apache.org/repos/asf/commons-math/blob/72a46bab/src/main/java/org/apache/commons/math4/util/MathArrays.java
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diff --git a/src/main/java/org/apache/commons/math4/util/MathArrays.java b/src/main/java/org/apache/commons/math4/util/MathArrays.java
index 86f67fd..3d8330f 100644
--- a/src/main/java/org/apache/commons/math4/util/MathArrays.java
+++ b/src/main/java/org/apache/commons/math4/util/MathArrays.java
@@ -766,6 +766,28 @@ public class MathArrays {
}
/**
+ * A helper data structure holding a double and an integer value.
+ */
+ private static class PairDoubleInteger {
+
+ private final double key;
+ private final int value;
+
+ public PairDoubleInteger(double key, int value) {
+ this.key = key;
+ this.value = value;
+ }
+
+ public double getKey() {
+ return key;
+ }
+
+ public int getValue() {
+ return value;
+ }
+ }
+
+ /**
* Sort an array in place and perform the same reordering of entries on
* other arrays. This method works the same as the other
* {@link #sortInPlace(double[], double[][]) sortInPlace} method, but
@@ -807,26 +829,26 @@ public class MathArrays {
}
// Associate each abscissa "x[i]" with its index "i".
- final List<Pair<Double, Integer>> list
- = new ArrayList<Pair<Double, Integer>>(len);
+ final List<PairDoubleInteger> list
+ = new ArrayList<PairDoubleInteger>(len);
for (int i = 0; i < len; i++) {
- list.add(new Pair<Double, Integer>(x[i], i));
+ list.add(new PairDoubleInteger(x[i], i));
}
// Create comparators for increasing and decreasing orders.
- final Comparator<Pair<Double, Integer>> comp
+ final Comparator<PairDoubleInteger> comp
= dir == MathArrays.OrderDirection.INCREASING ?
- new Comparator<Pair<Double, Integer>>() {
+ new Comparator<PairDoubleInteger>() {
@Override
- public int compare(Pair<Double, Integer> o1,
- Pair<Double, Integer> o2) {
- return o1.getKey().compareTo(o2.getKey());
+ public int compare(PairDoubleInteger o1,
+ PairDoubleInteger o2) {
+ return Double.compare(o1.getKey(), o2.getKey());
}
- } : new Comparator<Pair<Double,Integer>>() {
+ } : new Comparator<PairDoubleInteger>() {
@Override
- public int compare(Pair<Double, Integer> o1,
- Pair<Double, Integer> o2) {
- return o2.getKey().compareTo(o1.getKey());
+ public int compare(PairDoubleInteger o1,
+ PairDoubleInteger o2) {
+ return Double.compare(o2.getKey(), o1.getKey());
}
};
@@ -838,7 +860,7 @@ public class MathArrays {
// Retrieve indices of original locations.
final int[] indices = new int[len];
for (int i = 0; i < len; i++) {
- final Pair<Double, Integer> e = list.get(i);
+ final PairDoubleInteger e = list.get(i);
x[i] = e.getKey();
indices[i] = e.getValue();
}