/**
* Creates a copy of a given {@code DoubleVector} with the same type as the original.
*
* @param source The {@code Vector} to copy.
* @return A copy of {@code source} with the same type.
*/
public static DoubleVector copyOf(DoubleVector source) {
if (source == null) return null;
DoubleVector result = null;
if (source instanceof SparseDoubleVector) {
result = new CompactSparseVector(source.length());
copyFromSparseVector(result, source);
} else if (source instanceof DenseVector || source instanceof ScaledDoubleVector) {
result = new DenseVector(source.length());
for (int i = 0; i < source.length(); ++i) result.set(i, source.get(i));
} else if (source instanceof AmortizedSparseVector) {
result = new AmortizedSparseVector(source.length());
copyFromSparseVector(result, source);
} else if (source instanceof DoubleVectorView) {
DoubleVectorView view = (DoubleVectorView) source;
return copyOf(view.getOriginalVector());
} else {
// Create a copy of the given class using reflection. This code
// assumes that the given implemenation of Vector has a constructor
// which accepts another Vector.
try {
Class<? extends DoubleVector> sourceClazz = source.getClass();
Constructor<? extends DoubleVector> constructor =
sourceClazz.getConstructor(DoubleVector.class);
result = (DoubleVector) constructor.newInstance(source);
} catch (Exception e) {
throw new Error(e);
}
}
return result;
}
/**
* Copies values from a {@code SparseVector} into another vector
*
* @param destination The {@code Vector to copy values into.
* @param source The {@code @SparseVector} to copy values from.
*/
private static void copyFromSparseVector(DoubleVector destination, DoubleVector source) {
int[] nonZeroIndices = ((SparseVector) source).getNonZeroIndices();
for (int index : nonZeroIndices) destination.set(index, source.get(index));
}