[Base] Added reorderVector

BaseLib/reorderVector.h

+/**
+ * \brief Reorder vector elements by given indices
+ *
+ * \copyright
+ * Copyright (c) 2012-2016, OpenGeoSys Community (http://www.opengeosys.org)
+ *            Distributed under a Modified BSD License.
+ *              See accompanying file LICENSE.txt or
+ *              http://www.opengeosys.org/project/license
+ *
+ * \file   reorderVector.h
+ * Created on October 13, 2016, 5:37 PM
+ */
+
+#ifndef OGS_BASELIB_REORDERVECTOR_H
+#define OGS_BASELIB_REORDERVECTOR_H
+
+namespace BaseLib
+{
+/**
+ * Reorder a vector by a given index vector.
+ *  From
+ *  <a href="reorderV">http://stackoverflow.com/questions/838384/reorder-vector-using-a-vector-of-indices</a>
+ *
+ *  Note: The simple version on that page is taken, which is good enough in performance
+ *        for medium size vectors.
+ */
+template <typename ValueType, typename IndexType>
+void reorderVector(std::vector<ValueType>& v,
+                   std::vector<IndexType> const& order)
+{
+    for (std::size_t s = 1, d; s < order.size(); ++s)
+    {
+        for (d = order[s]; d < s; d = order[d]);
+        if (d == s)
+            while (d = order[d], d != s)
+                std::swap(v[s], v[d]);
+    }
+}
+
+} // end of namespace
+#endif /* OGS_BASELIB_REORDERVECTOR_H */
+

Tests/BaseLib/TestreorderVector.cpp

+/**
+ * \copyright
+ * Copyright (c) 2012-2016, OpenGeoSys Community (http://www.opengeosys.org)
+ *            Distributed under a Modified BSD License.
+ *              See accompanying file LICENSE.txt or
+ *              http://www.opengeosys.org/project/license
+ *
+ *   \file TestreorderVector.cpp
+ *
+ *   Created on August 14, 2016, 10:01 AM
+ *
+ */
+
+#include <vector>
+
+#include <gtest/gtest.h>
+
+#include "BaseLib/reorderVector.h"
+
+TEST(BaseLib_reorderVector, testreorderVector)
+{
+    std::vector<double> vec {2016.0, 1996.0, 2006.0, 1986.0};
+    std::vector<int> order {3, 1, 2, 0};
+    BaseLib::reorderVector(vec, order);
+
+    EXPECT_EQ(1986.0, vec[0]);
+    EXPECT_EQ(1996.0, vec[1]);
+    EXPECT_EQ(2006.0, vec[2]);
+    EXPECT_EQ(2016.0, vec[3]);
+}