PR review comments.

Signed-off-by: Robert Altena <Rob@Ra-ai.com>

nd4j-examples/src/main/java/org/nd4j/examples/Nd4jEx16_Serialization.java

@@ -4,6 +4,7 @@
 import org.nd4j.linalg.factory.Nd4j;
 
 import java.io.*;
+import java.util.Map;
 import java.util.Objects;
 
 /**
@@ -12,47 +13,64 @@
  */
 public class Nd4jEx16_Serialization {
 
-    public static void main(String[] args) throws IOException {
+    public static void main(String[] args) throws Exception {
         ClassLoader loader = Nd4jEx16_Serialization.class.getClassLoader();  // used to read files from resources.
 
         // 1. binary format from stream.
         INDArray arrWrite = Nd4j.linspace(1,25,25).reshape(5,5);
         String pathname = "tmp.bin";
-        DataOutputStream sWrite = new DataOutputStream(new FileOutputStream(new File(pathname )));
-        Nd4j.write(arrWrite, sWrite);
 
-        DataInputStream sRead = new DataInputStream(new FileInputStream(new File(pathname )));
-        INDArray arrRead = Nd4j.read(sRead);
+        try(DataOutputStream sWrite = new DataOutputStream(new FileOutputStream(new File(pathname )))){
+            Nd4j.write(arrWrite, sWrite);
+        }
+
+        INDArray arrRead;
+        try(DataInputStream sRead = new DataInputStream(new FileInputStream(new File(pathname )))){
+            arrRead = Nd4j.read(sRead);
+        }
+
         // We now have our test matrix in arrRead
-        System.out.println("Read from binary format:" );
+        System.out.println("Read from binary stream:" );
         System.out.println(arrRead );
 
 
-        // 2. Read the numpy npy (and npz) formats:
-        File file =  new File( Objects.requireNonNull(loader.getResource("twentyfive.npy")).getFile());
+        // 2. Write and read the numpy npy format:
+        File file =  new File("nd4j.npy" );
+        Nd4j.writeAsNumpy(arrRead, file ); // Try to read this file from Python:   y = np.load('nd4j.npy')
+
+        arrRead = Nd4j.createFromNpyFile(file); // We can read these files from nd4j.
+        System.out.println();
+        System.out.println("Read from Numpy .npy format:" );
+        System.out.println(arrRead);
+
+
+        // 3. Read the numpy npz format:
+        file =  new File( Objects.requireNonNull(loader.getResource("numpyz.npz")).getFile());
 
-        INDArray x = Nd4j.createFromNpyFile(file); // Nd4j.createFromNpzFile for npz Numpy files.
+        Map<String, INDArray> arrayMap = Nd4j.createFromNpzFile(file); //We get a map reading an .npz file.
         System.out.println();
-        System.out.println("Read from Numpy .npyformat:" );
-        System.out.println(x);
+        System.out.println("Read from Numpy .npz format:" );
+        System.out.println(arrayMap.get("arr_0")); //We know there are 2 arrays in the .npz file.
+        System.out.println(arrayMap.get("arr_1"));
 
 
-        // 3. binary format from file.
+        // 4. binary format from file.
         file =  new File(pathname);
         Nd4j.saveBinary(arrWrite, file);
         arrRead = Nd4j.readBinary(file );
         System.out.println();
-        System.out.println("Read from Numpy .npyformat:" );
+        System.out.println("Read from binary format:" );
         System.out.println(arrRead);
 
 
-        // 4. read a csv file.
+        // 5. read a csv file.
         file =  new File( Objects.requireNonNull(loader.getResource("twentyfive.csv")).getFile());
         String Filename = file.getAbsolutePath();
         arrRead  = Nd4j.readNumpy(Filename, ",");
         System.out.println();
         System.out.println("Read from csv format:" );
         System.out.println(arrRead);
+
     }
 
 }