MATH-515

"copyOf" methods (for "int" and "double" arrays).


git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1071596 13f79535-47bb-0310-9956-ffa450edef68

src/main/java/org/apache/commons/math/util/MathUtils.java

@@ -2220,10 +2220,7 @@ public final class MathUtils {
      * @return the copied array.
      */
      public static int[] copyOf(int[] source) {
-         final int len = source.length;
-         final int[] output = new int[len];
-         System.arraycopy(source, 0, output, 0, len);
-         return output;
+         return copyOf(source, source.length);
      }
 
     /**
@@ -2233,9 +2230,36 @@ public final class MathUtils {
      * @return the copied array.
      */
      public static double[] copyOf(double[] source) {
-         final int len = source.length;
+         return copyOf(source, source.length);
+     }
+
+    /**
+     * Creates a copy of the {@code source} array.
+     *
+     * @param source Array to be copied.
+     * @param len Number of entries to copy. If smaller then the source
+     * length, the copy will be truncated, if larger it will padded with
+     * zeroes.
+     * @return the copied array.
+     */
+    public static int[] copyOf(int[] source, int len) {
+         final int[] output = new int[len];
+         System.arraycopy(source, 0, output, 0, FastMath.min(len, source.length));
+         return output;
+     }
+
+    /**
+     * Creates a copy of the {@code source} array.
+     *
+     * @param source Array to be copied.
+     * @param len Number of entries to copy. If smaller then the source
+     * length, the copy will be truncated, if larger it will padded with
+     * zeroes.
+     * @return the copied array.
+     */
+    public static double[] copyOf(double[] source, int len) {
          final double[] output = new double[len];
-         System.arraycopy(source, 0, output, 0, len);
+         System.arraycopy(source, 0, output, 0, FastMath.min(len, source.length));
          return output;
      }
 }

src/test/java/org/apache/commons/math/util/MathUtilsTest.java

@@ -1557,6 +1557,35 @@ public final class MathUtilsTest extends TestCase {
         }
     }
 
+    public void testCopyOfInt2() {
+        final int[] source = { Integer.MIN_VALUE,
+                               -1, 0, 1, 3, 113, 4769,
+                               Integer.MAX_VALUE };
+        final int offset = 3;
+        final int[] dest = MathUtils.copyOf(source, source.length - offset);
+
+        assertEquals(dest.length, source.length - offset);
+        for (int i = 0; i < source.length - offset; i++) {
+            assertEquals(source[i], dest[i]);
+        }
+    }
+
+    public void testCopyOfInt3() {
+        final int[] source = { Integer.MIN_VALUE,
+                               -1, 0, 1, 3, 113, 4769,
+                               Integer.MAX_VALUE };
+        final int offset = 3;
+        final int[] dest = MathUtils.copyOf(source, source.length + offset);
+
+        assertEquals(dest.length, source.length + offset);
+        for (int i = 0; i < source.length; i++) {
+            assertEquals(source[i], dest[i]);
+        }
+        for (int i = source.length; i < source.length + offset; i++) {
+            assertEquals(0, dest[i], 0);
+        }
+    }
+
     public void testCopyOfDouble() {
         final double[] source = { Double.NEGATIVE_INFINITY,
                                   -Double.MAX_VALUE,
@@ -1573,4 +1602,43 @@ public final class MathUtilsTest extends TestCase {
             assertEquals(source[i], dest[i], 0);
         }
     }
+
+    public void testCopyOfDouble2() {
+        final double[] source = { Double.NEGATIVE_INFINITY,
+                                  -Double.MAX_VALUE,
+                                  -1, 0,
+                                  Double.MIN_VALUE,
+                                  Math.ulp(1d),
+                                  1, 3, 113, 4769,
+                                  Double.MAX_VALUE,
+                                  Double.POSITIVE_INFINITY };
+        final int offset = 3;
+        final double[] dest = MathUtils.copyOf(source, source.length - offset);
+
+        assertEquals(dest.length, source.length - offset);
+        for (int i = 0; i < source.length - offset; i++) {
+            assertEquals(source[i], dest[i], 0);
+        }
+    }
+
+    public void testCopyOfDouble3() {
+        final double[] source = { Double.NEGATIVE_INFINITY,
+                                  -Double.MAX_VALUE,
+                                  -1, 0,
+                                  Double.MIN_VALUE,
+                                  Math.ulp(1d),
+                                  1, 3, 113, 4769,
+                                  Double.MAX_VALUE,
+                                  Double.POSITIVE_INFINITY };
+        final int offset = 3;
+        final double[] dest = MathUtils.copyOf(source, source.length + offset);
+
+        assertEquals(dest.length, source.length + offset);
+        for (int i = 0; i < source.length; i++) {
+            assertEquals(source[i], dest[i], 0);
+        }
+        for (int i = source.length; i < source.length + offset; i++) {
+            assertEquals(0, dest[i], 0);
+        }
+    }
 }