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Merge branch 'feature-MATH-1339' into develop 

Fixes the following issue (see JIRA):
  MATH-1339
This commit is contained in:
Gilles 2016-04-22 00:16:35 +02:00
parent 78ebedb0f1 55fd738c86
commit 73952558a1
2 changed files with 19 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
src/main/java/org/apache/commons/math4/util/MathArrays.java
View File

@ -1617,8 +1617,7 @@ public class MathArrays {
if (i == start) {
target = start;
} else {
// NumberIsTooLargeException cannot occur.
target = new UniformIntegerDistribution(start, i).createSampler(rng).sample();
target = rng.nextInt(i - start + 1) + start;
}
final int temp = list[target];
list[target] = list[i];
@ -1632,8 +1631,7 @@ public class MathArrays {
if (i == start) {
target = start;
} else {
// NumberIsTooLargeException cannot occur.
target = new UniformIntegerDistribution(i, start).createSampler(rng).sample();
target = rng.nextInt(start - i + 1) + i;
}
final int temp = list[target];
list[target] = list[i];

17
src/test/java/org/apache/commons/math4/util/MathArraysTest.java
View File

@ -1107,6 +1107,23 @@ public class MathArraysTest {
}
}
@Test
public void testShuffleNoDuplicates() {
final int n = 100;
final int[] orig = MathArrays.natural(n);
MathArrays.shuffle(orig);
// Test that all (unique) entries exist in the shuffled array.
final int[] count = new int[n];
for (int i = 0; i < n; i++) {
count[orig[i]] += 1;
}
for (int i = 0; i < n; i++) {
Assert.assertEquals(1, count[i]);
}
}
@Test
public void testShuffleTail() {
final int[] orig = new int[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };