Added the sum_rows() and sum_cols() functions.

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%403587

dlib/matrix/matrix_utilities.h

@@ -1417,6 +1417,96 @@ namespace dlib
         return val;
     }
 
+// ----------------------------------------------------------------------------------------
+
+    struct op_sumr 
+    {
+        template <typename EXP>
+        struct op : has_destructive_aliasing
+        {
+            const static long cost = EXP::cost;
+            const static long NR = 1;
+            const static long NC = EXP::NC;
+            typedef typename EXP::type type;
+            typedef const typename EXP::type const_ret_type;
+            typedef typename EXP::mem_manager_type mem_manager_type;
+            template <typename M>
+            static const_ret_type apply ( const M& m, long , long c)
+            { 
+                type temp = m(0,c);
+                for (long r = 1; r < m.nr(); ++r)
+                    temp += m(r,c);
+                return temp; 
+            }
+
+            template <typename M>
+            static long nr (const M& ) { return 1; }
+            template <typename M>
+            static long nc (const M& m) { return m.nc(); }
+        }; 
+    };
+
+    template <
+        typename EXP
+        >
+    const matrix_unary_exp<EXP,op_sumr> sum_rows (
+        const matrix_exp<EXP>& m
+    )
+    {
+        DLIB_ASSERT(m.size() > 0 , 
+                    "\tconst matrix_exp sum_rows(m)"
+                    << "\n\t The matrix can't be empty"
+                    << "\n\t m.size(): " << m.size() 
+        );
+        typedef matrix_unary_exp<EXP,op_sumr> exp;
+        return exp(m.ref());
+    }
+
+// ----------------------------------------------------------------------------------------
+
+    struct op_sumc 
+    {
+        template <typename EXP>
+        struct op : has_destructive_aliasing
+        {
+            const static long cost = EXP::cost;
+            const static long NR = EXP::NR;
+            const static long NC = 1;
+            typedef typename EXP::type type;
+            typedef const typename EXP::type const_ret_type;
+            typedef typename EXP::mem_manager_type mem_manager_type;
+            template <typename M>
+            static const_ret_type apply ( const M& m, long r, long )
+            { 
+                type temp = m(r,0);
+                for (long c = 1; c < m.nc(); ++c)
+                    temp += m(r,c);
+                return temp; 
+            }
+
+            template <typename M>
+            static long nr (const M& m) { return m.nr(); }
+            template <typename M>
+            static long nc (const M& ) { return 1; }
+        }; 
+    };
+
+    template <
+        typename EXP
+        >
+    const matrix_unary_exp<EXP,op_sumc> sum_cols (
+        const matrix_exp<EXP>& m
+    )
+    {
+        DLIB_ASSERT(m.size() > 0 , 
+                    "\tconst matrix_exp sum_cols(m)"
+                    << "\n\t The matrix can't be empty"
+                    << "\n\t m.size(): " << m.size() 
+        );
+        typedef matrix_unary_exp<EXP,op_sumc> exp;
+        return exp(m.ref());
+    }
+
 // ----------------------------------------------------------------------------------------
 
     template <

dlib/matrix/matrix_utilities_abstract.h

@@ -1267,6 +1267,42 @@ namespace dlib
             - returns the sum of all elements in m
     !*/
 
+// ----------------------------------------------------------------------------------------
+
+    const matrix_exp sum_rows (
+        const matrix_exp& m
+    );
+    /*!
+        requires
+            - m.size() > 0
+        ensures
+            - returns a row matrix that contains the sum of all the rows in m. 
+            - returns a matrix M such that
+                - M::type == the same type that was in m
+                - M.nr() == 1
+                - M.nc() == m.nc()
+                - for all valid i:
+                    - M(i) == sum(colm(m,i)) 
+    !*/
+
+// ----------------------------------------------------------------------------------------
+
+    const matrix_exp sum_cols (
+        const matrix_exp& m
+    );
+    /*!
+        requires
+            - m.size() > 0
+        ensures
+            - returns a column matrix that contains the sum of all the columns in m. 
+            - returns a matrix M such that
+                - M::type == the same type that was in m
+                - M.nr() == m.nr() 
+                - M.nc() == 1
+                - for all valid i:
+                    - M(i) == sum(rowm(m,i)) 
+    !*/
+
 // ----------------------------------------------------------------------------------------
 
     const matrix_exp::type prod (

dlib/test/matrix3.cpp

@@ -938,6 +938,50 @@ namespace
 
             DLIB_TEST(pointer_to_matrix(&v[0], 2, 3) == a);
         }
+
+        {
+            matrix<int> a(3,4);
+            matrix<int> b(3,1), c(1,4);
+
+            a = 1, 2, 3, 6,
+                4, 5, 6, 9,
+                1, 1, 1, 3;
+
+            b(0) = sum(rowm(a,0));
+            b(1) = sum(rowm(a,1));
+            b(2) = sum(rowm(a,2));
+
+            c(0) = sum(colm(a,0));
+            c(1) = sum(colm(a,1));
+            c(2) = sum(colm(a,2));
+            c(3) = sum(colm(a,3));
+
+            DLIB_TEST(sum_cols(a) == b);
+            DLIB_TEST(sum_rows(a) == c);
+
+        }
+
+        {
+            matrix<int,3,4> a;
+            matrix<int> b(3,1), c(1,4);
+
+            a = 1, 2, 3, 6,
+                4, 5, 6, 9,
+                1, 1, 1, 3;
+
+            b(0) = sum(rowm(a,0));
+            b(1) = sum(rowm(a,1));
+            b(2) = sum(rowm(a,2));
+
+            c(0) = sum(colm(a,0));
+            c(1) = sum(colm(a,1));
+            c(2) = sum(colm(a,2));
+            c(3) = sum(colm(a,3));
+
+            DLIB_TEST(sum_cols(a) == b);
+            DLIB_TEST(sum_rows(a) == c);
+
+        }
     }