1 files changed, 46 insertions, 19 deletions

diff --git a/ot/lp/EMD_wrapper.cpp b/ot/lp/EMD_wrapper.cpp
index 3ca7319..2aa44c1 100644
--- a/ot/lp/EMD_wrapper.cpp
+++ b/ot/lp/EMD_wrapper.cpp
@@ -111,23 +111,19 @@ int EMD_wrap_return_sparse(int n1, int n2, double *X, double *Y, double *D,
                     long *iG, long *jG, double *G,
                     double* alpha, double* beta, double *cost, int maxIter)  {
     // beware M and C anre strored in row major C style!!!
-     int n, m, i, cur;
+
+    // Get the number of non zero coordinates for r and c and vectors
+    int n, m, i, cur;
 
     typedef FullBipartiteDigraph Digraph;
     DIGRAPH_TYPEDEFS(FullBipartiteDigraph);
 
-    std::vector<int> indI(n), indJ(m);
-    std::vector<double> weights1(n), weights2(m);
-    Digraph di(n, m);
-    NetworkSimplexSimple<Digraph,double,double, node_id_type> net(di, true, n+m, n*m, maxIter);
-
-    // Get the number of non zero coordinates for r and c and vectors
+    // Get the number of non zero coordinates for r and c
     n=0;
     for (int i=0; i<n1; i++) {
         double val=*(X+i);
         if (val>0) {
-            weights1[ n ] = val;
-            indI[n++]=i;
+            n++;
         }else if(val<0){
 			return INFEASIBLE;
 		}
@@ -136,14 +132,42 @@ int EMD_wrap_return_sparse(int n1, int n2, double *X, double *Y, double *D,
     for (int i=0; i<n2; i++) {
         double val=*(Y+i);
         if (val>0) {
-            weights2[ m ] = -val;
-            indJ[m++]=i;
+            m++;
         }else if(val<0){
 			return INFEASIBLE;
 		}
     }
 
     // Define the graph
+
+    std::vector<int> indI(n), indJ(m);
+    std::vector<double> weights1(n), weights2(m);
+    Digraph di(n, m);
+    NetworkSimplexSimple<Digraph,double,double, node_id_type> net(di, true, n+m, n*m, maxIter);
+
+    // Set supply and demand, don't account for 0 values (faster)
+
+    cur=0;
+    for (int i=0; i<n1; i++) {
+        double val=*(X+i);
+        if (val>0) {
+            weights1[ cur ] = val;
+            indI[cur++]=i;
+        }
+    }
+
+    // Demand is actually negative supply...
+
+    cur=0;
+    for (int i=0; i<n2; i++) {
+        double val=*(Y+i);
+        if (val>0) {
+            weights2[ cur ] = -val;
+            indJ[cur++]=i;
+        }
+    }
+
+    // Define the graph
     net.supplyMap(&weights1[0], n, &weights2[0], m);
 
     // Set the cost of each edge
@@ -166,14 +190,17 @@ int EMD_wrap_return_sparse(int n1, int n2, double *X, double *Y, double *D,
             int i = di.source(a);
             int j = di.target(a);
             double flow = net.flow(a);
-            *cost += flow * (*(D+indI[i]*n2+indJ[j-n]));
-
-            *(G+cur) = flow;
-            *(iG+cur) = indI[i];
-            *(jG+cur) = indJ[j];
-            *(alpha + indI[i]) = -net.potential(i);
-            *(beta + indJ[j-n]) = net.potential(j);
-            cur++;
+            if (flow>0)
+            {
+                *cost += flow * (*(D+indI[i]*n2+indJ[j-n]));
+
+                *(G+cur) = flow;
+                *(iG+cur) = indI[i];
+                *(jG+cur) = indJ[j-n];
+                *(alpha + indI[i]) = -net.potential(i);
+                *(beta + indJ[j-n]) = net.potential(j);
+                cur++;
+            }
         }
 
     }