Merge pull request #2374 from tdegeus/average2

average: fixing overload issue for axis argument

Author: JohanMabille

docs/source/api/xmath.rst

@@ -276,6 +276,8 @@ Mathematical functions
 +-----------------------------------------------+---------------------------------------------------------------------+
 | :ref:`mean <mean-function-reference>`         | mean of elements over given axes                                    |
 +-----------------------------------------------+---------------------------------------------------------------------+
+| :ref:`average <average-function-reference>`   | weighted average along the specified axis                           |
++-----------------------------------------------+---------------------------------------------------------------------+
 | :ref:`variance <variance-function-reference>` | variance of elements over given axes                                |
 +-----------------------------------------------+---------------------------------------------------------------------+
 | :ref:`stddev <stddev-function-reference>`     | standard deviation of elements over given axes                      |

include/xtensor/xmath.hpp

@@ -1999,6 +1999,13 @@ namespace detail {
         return sum<T>(std::forward<E>(e) * std::move(weights_view), std::move(ax), ev) / std::move(scl);
     }
 
+    template <class T = void, class E, class W, class X, class EVS = DEFAULT_STRATEGY_REDUCERS,
+              XTL_REQUIRES(is_reducer_options<EVS>, xtl::is_integral<X>)>
+    inline auto average(E&& e, W&& weights, X axis, EVS ev = EVS())
+    {
+        return average(std::forward<E>(e), std::forward<W>(weights), {axis}, std::forward<EVS>(ev));
+    }
+
     template <class T = void, class E, class W, class X, std::size_t N, class EVS = DEFAULT_STRATEGY_REDUCERS>
     inline auto average(E&& e, W&& weights, const X(&axes)[N], EVS ev = EVS())
     {

test/test_xmath.cpp

@@ -854,6 +854,41 @@ namespace xt
         EXPECT_EQ(res5[0], 8.0);
     }
 
+    /********************
+     * Mean and average *
+     ********************/
+
+    TEST(xmath, mean)
+    {
+        xt::xtensor<double,2> v = {{1.0, 1.0, 1.0}, {2.0, 2.0, 2.0}};
+        xt::xtensor<double,1> m0 = {1.5, 1.5, 1.5};
+        xt::xtensor<double,1> m1 = {1.0, 2.0};
+        double m = 9.0 / 6.0;
+
+        EXPECT_TRUE(xt::all(xt::equal(xt::mean(v, 0), m0)));
+        EXPECT_TRUE(xt::all(xt::equal(xt::mean(v, {0}), m0)));
+        EXPECT_TRUE(xt::all(xt::equal(xt::mean(v, 1), m1)));
+        EXPECT_TRUE(xt::all(xt::equal(xt::mean(v, {1}), m1)));
+        EXPECT_EQ(xt::mean(v)(), m);
+        EXPECT_EQ(xt::mean(v, {0, 1})(), m);
+    }
+
+    TEST(xmath, average)
+    {
+        xt::xtensor<double,2> v = {{1.0, 1.0, 1.0}, {2.0, 2.0, 2.0}};
+        xt::xtensor<double,2> w = {{2.0, 2.0, 2.0}, {2.0, 2.0, 2.0}};
+        xt::xtensor<double,1> m0 = {1.5, 1.5, 1.5};
+        xt::xtensor<double,1> m1 = {1.0, 2.0};
+        double m = 9.0 / 6.0;
+
+        EXPECT_TRUE(xt::all(xt::equal(xt::average(v, w, 0), m0)));
+        EXPECT_TRUE(xt::all(xt::equal(xt::average(v, w, {0}), m0)));
+        EXPECT_TRUE(xt::all(xt::equal(xt::average(v, w, 1), m1)));
+        EXPECT_TRUE(xt::all(xt::equal(xt::average(v, w, {1}), m1)));
+        EXPECT_EQ(xt::average(v, w)(), m);
+        EXPECT_EQ(xt::average(v, w, {0, 1})(), m);
+    }
+
     /************************
      * Linear interpolation *
      ************************/