Make LSTM config consisternt with GenerateTxtModel.java, clean up static final Strings in MelodyStrings.java so they're easier to modify

Author: DonaldAlan

dl4j-examples/src/main/java/org/deeplearning4j/examples/wip/advanced/modelling/melodl4j/MelodyModelingExample.java

@@ -36,6 +36,7 @@
 import org.nd4j.linalg.api.ndarray.INDArray;
 import org.nd4j.linalg.dataset.DataSet;
 import org.nd4j.linalg.factory.Nd4j;
+import org.nd4j.linalg.learning.config.Adam;
 import org.nd4j.linalg.learning.config.RmsProp;
 import org.nd4j.linalg.lossfunctions.LossFunctions;
 
@@ -120,9 +121,10 @@ public static void main(String[] args) throws Exception {
 
         //Set up network configuration:
         MultiLayerConfiguration conf = new NeuralNetConfiguration.Builder()
-            .updater(new RmsProp(0.1))
-            .seed(12345)
-            .l2(0.001)
+            //.updater(new RmsProp(0.1))
+            .updater(new Adam(0.005))
+            .seed(System.currentTimeMillis()) // So each run generates new melodies
+            .l2(0.0001)
             .weightInit(WeightInit.XAVIER)
             .list()
             .layer(0, new LSTM.Builder().nIn(iter.inputColumns()).nOut(lstmLayerSize)
@@ -136,7 +138,6 @@ public static void main(String[] args) throws Exception {
             .backpropType(BackpropType.TruncatedBPTT).tBPTTForwardLength(tbpttLength).tBPTTBackwardLength(tbpttLength)
             .build();
 
-
         learn(miniBatchSize, exampleLength, numEpochs, generateSamplesEveryNMinibatches, nSamplesToGenerate, nCharactersToSample, generationInitialization, rng, startTime, iter, conf);
     }
 

dl4j-examples/src/main/java/org/deeplearning4j/examples/wip/advanced/modelling/melodl4j/MelodyStrings.java

@@ -35,27 +35,32 @@ public class MelodyStrings {
     public static final char lowestPitchGapChar = 'A';
     public static final char REST_CHAR = ' ';
 
-    // We allow pitch gaps between -12 and +12, inclusive.
-    // If you want to change the allowed gap, you will have to change the characters in PITCH_GAP_CHARS_NEGATIVE and  PITCH_GAP_CHARS_POSITIVE
+    // As written now, it allows pitch gaps between -12 and +12, inclusive.
+    // If you want to change the allowed gap, you will have to change the characters in PITCH_GAP_CHARS_POSITIVE
+    // and PITCH_GAP_CHARS_NEGATIVE
+
+    // There are thirteen chars in pitchGapCharsPositive because the first one ('M') indicates a zero pitch gap.
+    // "M" indicates delta=0. "N" indicates delta=1, 'O' indicates delta=2, etc.
+    public static final String PITCH_GAP_CHARS_POSITIVE = "MNOPQRSTUVWXY";
+
+    public static int MAX_POSITIVE_PITCH_GAP = PITCH_GAP_CHARS_POSITIVE.length()-1; // -1 because the first char is for zero.
+    public static final char ZERO_PITCH_DELTA_CHAR = PITCH_GAP_CHARS_POSITIVE.charAt(0);
+    public static final char MAX_POSITIVE_PITCH_DELTA_CHAR = PITCH_GAP_CHARS_POSITIVE.charAt(PITCH_GAP_CHARS_POSITIVE.length()-1);
 
-    public static int MAX_POSITIVE_PITCH_GAP = 12;
     // The order of characters below is intended to simplify the learning of pitch gaps, because increasing
-    // characters correspond to increasing pitch gaps.  The string must end with 'A'.
-    public static final String PITCH_GAP_CHARS_NEGATIVE = "LKJIHGFEDCBA"; // "L" indicates delta=-1. "K" indicates -2,...
+    // characters correspond to increasing pitch gaps.  (Whether this convention simplifies learning pitches
+    // depends on which learning algorithm is used.) The string must end with 'A'.
+    // "L" indicates delta=-1. "K" indicates delta = -2, 'J' indicates delta = -3, etc.
+    public static final String PITCH_GAP_CHARS_NEGATIVE = "LKJIHGFEDCBA";
 
     public static final char FIRST_PITCH_CHAR_NEGATIVE =  PITCH_GAP_CHARS_NEGATIVE.charAt(0);
 
-    // There are thirteen chars in pitchGapCharsPositive because the first one ('M') indicates a zero pitch gap.
-    public static final String PITCH_GAP_CHARS_POSITIVE = "MNOPQRSTUVWXY"; // "M" indicates delta=0. "N" indicates 1, ...
-    public static final char ZERO_PITCH_DELTA_CHAR = 'M';
-    public static final char MAX_POSITIVE_PITCH_DELTA_CHAR = 'Y';
-
     // durationDeltaParts determines how short durations can get. The shortest duration is 1/durationDeltaParts
     // as long as the average note length in the piece.
     public static int durationDeltaParts = 8;
     public static final String DURATION_CHARS = "]^_`abcdefghijklmnopqrstuvwxyz{|"; // 32 divisions, in ASCII order
 
-    public static final char FIRST_DURATION_CHAR = ']';
+    public static final char FIRST_DURATION_CHAR = DURATION_CHARS.charAt(0);
     public static final String allValidCharacters = getValidCharacters();
     // 13+13+1+32 = 59 possible characters.
     // ']' indicates the smallest pitch duration allowed (typically a 1/32 note or so).