AbstractRealVector.sparseIterator fails when vector has exactly one non-zero
entry
----------------------------------------------------------------------------------
Key: MATH-367
URL: https://issues.apache.org/jira/browse/MATH-367
Project: Commons Math
Issue Type: Bug
Affects Versions: 2.1, 2.2
Reporter: Albert Huang
Priority: Minor
The following program:
===
import java.util.Iterator;
import org.apache.commons.math.linear.*;
public class SparseIteratorTester
{
public static void main(String[] args) {
double vdata[] = { 0.0, 1.0, 0.0 };
RealVector v = new ArrayRealVector(vdata);
Iterator<RealVector.Entry> iter = v.sparseIterator();
while(iter.hasNext()) {
RealVector.Entry entry = iter.next();
System.out.printf("%d: %f\n", entry.getIndex(), entry.getValue());
}
}
}
===
generates this output:
1: 1.000000
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: -1
at
org.apache.commons.math.linear.ArrayRealVector.getEntry(ArrayRealVector.java:995)
at
org.apache.commons.math.linear.AbstractRealVector$EntryImpl.getValue(AbstractRealVector.java:850)
at test.SparseIteratorTester.main(SparseIteratorTester.java:13)
===
This patch fixes it, and simplifies AbstractRealVector.SparseEntryIterator
(sorry, i don't see any form entry for attaching a file)
===
Index: src/main/java/org/apache/commons/math/linear/AbstractRealVector.java
===================================================================
--- src/main/java/org/apache/commons/math/linear/AbstractRealVector.java
(revision 936985)
+++ src/main/java/org/apache/commons/math/linear/AbstractRealVector.java
(working copy)
@@ -18,6 +18,7 @@
package org.apache.commons.math.linear;
import java.util.Iterator;
+import java.util.NoSuchElementException;
import org.apache.commons.math.FunctionEvaluationException;
import org.apache.commons.math.MathRuntimeException;
@@ -875,40 +876,25 @@
/** Dimension of the vector. */
private final int dim;
- /** Temporary entry (reused on each call to {...@link #next()}. */
- private EntryImpl tmp = new EntryImpl();
-
- /** Current entry. */
+ /** Last entry returned by #next(). */
private EntryImpl current;
- /** Next entry. */
+ /** Next entry for #next() to return. */
private EntryImpl next;
/** Simple constructor. */
protected SparseEntryIterator() {
dim = getDimension();
current = new EntryImpl();
- if (current.getValue() == 0) {
- advance(current);
- }
- if(current.getIndex() >= 0){
- // There is at least one non-zero entry
- next = new EntryImpl();
- next.setIndex(current.getIndex());
+ next = new EntryImpl();
+ if(next.getValue() == 0)
advance(next);
- } else {
- // The vector consists of only zero entries, so deny having a
next
- current = null;
- }
}
- /** Advance an entry up to the next non null one.
+ /** Advance an entry up to the next nonzero value.
* @param e entry to advance
*/
protected void advance(EntryImpl e) {
- if (e == null) {
- return;
- }
do {
e.setIndex(e.getIndex() + 1);
} while (e.getIndex() < dim && e.getValue() == 0);
@@ -919,22 +905,17 @@
/** {...@inheritdoc} */
public boolean hasNext() {
- return current != null;
+ return next.getIndex() >= 0;
}
/** {...@inheritdoc} */
public Entry next() {
- tmp.setIndex(current.getIndex());
- if (next != null) {
- current.setIndex(next.getIndex());
- advance(next);
- if (next.getIndex() < 0) {
- next = null;
- }
- } else {
- current = null;
- }
- return tmp;
+ int index = next.getIndex();
+ if(index < 0)
+ throw new NoSuchElementException();
+ current.setIndex(index);
+ advance(next);
+ return current;
}
/** {...@inheritdoc} */
--
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