On Tue, 03 Nov 2015 18:07:50 +0100, Luc Maisonobe wrote:
Le 03/11/2015 15:33, Gilles a écrit :
On Tue, 03 Nov 2015 11:06:50 -0000, l...@apache.org wrote:
Fixed findbugs warning.
When defining compareTo, we should also define equals and hashcode.
Project: http://git-wip-us.apache.org/repos/asf/commons-math/repo
Commit:
http://git-wip-us.apache.org/repos/asf/commons-math/commit/04454fc0
Tree:
http://git-wip-us.apache.org/repos/asf/commons-math/tree/04454fc0
Diff:
http://git-wip-us.apache.org/repos/asf/commons-math/diff/04454fc0
Branch: refs/heads/MATH_3_X
Commit: 04454fc0096d5d388e10c5b13024b2a947a4e923
Parents: b72d446
Author: Luc Maisonobe <l...@apache.org>
Authored: Tue Nov 3 11:23:46 2015 +0100
Committer: Luc Maisonobe <l...@apache.org>
Committed: Tue Nov 3 11:23:46 2015 +0100
----------------------------------------------------------------------
.../commons/math3/ml/neuralnet/MapUtils.java | 24
+++++++++++++++++---
1 file changed, 21 insertions(+), 3 deletions(-)
----------------------------------------------------------------------
http://git-wip-us.apache.org/repos/asf/commons-math/blob/04454fc0/src/main/java/org/apache/commons/math3/ml/neuralnet/MapUtils.java
----------------------------------------------------------------------
diff --git
a/src/main/java/org/apache/commons/math3/ml/neuralnet/MapUtils.java
b/src/main/java/org/apache/commons/math3/ml/neuralnet/MapUtils.java
index 83036c2..6ef9327 100644
---
a/src/main/java/org/apache/commons/math3/ml/neuralnet/MapUtils.java
+++
b/src/main/java/org/apache/commons/math3/ml/neuralnet/MapUtils.java
@@ -17,14 +17,15 @@
package org.apache.commons.math3.ml.neuralnet;
-import java.util.HashMap;
+import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
+import java.util.HashMap;
import java.util.List;
-import java.util.ArrayList;
+
+import org.apache.commons.math3.exception.NoDataException;
import org.apache.commons.math3.ml.distance.DistanceMeasure;
import
org.apache.commons.math3.ml.neuralnet.twod.NeuronSquareMesh2D;
-import org.apache.commons.math3.exception.NoDataException;
import org.apache.commons.math3.util.Pair;
/**
@@ -320,5 +321,22 @@ public class MapUtils {
public int compareTo(PairNeuronDouble other) {
return Double.compare(this.value, other.value);
}
+
+ /** {@inheritDoc} */
+ @Override
+ public boolean equals(Object other) {
+ if (!(other instanceof PairNeuronDouble)) {
+ return false;
+ }
+ return Double.doubleToRawLongBits(value) ==
+ Double.doubleToRawLongBits(((PairNeuronDouble)
other).value);
+ }
+
+ /** {@inheritDoc} */
+ @Override
+ public int hashCode() {
+ return Double.valueOf(value).hashCode();
+ }
+
}
}
I think that in general, it is not correct to assume pair equality
by only taking "value" into account.
I also think that the default implementation provided the correct
semantics (for the sole usage of sorting).
Sure, but as the compareTo method did only use value, the equals
method
should be consistent with it. Otherwise, you could have compareTo
return
0 when equals does not return true for example.
It is plain wrong (in general) to consider two objects equal just
because they
have the same rank according to an ordering based on part of their
properties.
[It's akin to saying e.g. that two books are the same, because they
happen
to have the same price tag.]
But it was perhaps a bad design choice to have "PairNeuronDouble"
implement
"Comparable".
I propose to use an explicit "Comparator" in order to fix the problem.
Best,
Gilles
best regards,
Luc
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