fix #69 : always use US locale when saving matrix

src/main/org/nlogo/extensions/nw/jung/io/Matrix.scala

@@ -3,25 +3,37 @@
 package org.nlogo.extensions.nw.jung.io
 
 import java.util.Random
-
 import org.nlogo.agent.AgentSet
 import org.nlogo.agent.Link
 import org.nlogo.agent.Turtle
 import org.nlogo.api.ExtensionException
 import org.nlogo.extensions.nw.jung.DummyGraph
 import org.nlogo.extensions.nw.jung.factoryFor
-
 import edu.uci.ics.jung
+import edu.uci.ics.jung.algorithms.matrix.GraphMatrixOperations
 
 object Matrix {
 
   def save(graph: jung.graph.Graph[Turtle, Link], filename: String) {
     if (org.nlogo.workspace.AbstractWorkspace.isApplet)
       throw new ExtensionException("Cannot save matrix file when in applet mode.")
-    new jung.io.MatrixFile[Turtle, Link](
-      null, // TODO: provide weight key (null means 1) (issue #19) 
-      null, null, null // no factories needed for save
-      ).save(graph, filename)
+    /* This is almost a line for line copy of jung.io.MatrixFile.save, the major
+     * difference being that it explicitly uses the US locale to make sure entries
+     * use the dot decimal separator (see issue #69) */
+    try {
+      val writer = new java.io.BufferedWriter(new java.io.FileWriter(filename))
+      val matrix = GraphMatrixOperations.graphToSparseMatrix(graph, null) // TODO: provide weights
+      for (i <- 0 until matrix.rows) {
+        for (j <- 0 until matrix.columns) {
+          val w = matrix.getQuick(i, j)
+          writer.write("%4.2f ".formatLocal(java.util.Locale.US, w))
+        }
+        writer.write("\n")
+      }
+      writer.close()
+    } catch {
+      case e: Exception => throw new ExtensionException("Error saving file: " + filename, e)
+    }
   }
 
   def load(filename: String, turtleBreed: AgentSet, linkBreed: AgentSet, rng: Random) = {