Android Open Source - IntelligentCarForAndroid Neural Network

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Back to project page IntelligentCarForAndroid.

License

The source code is released under:

Apache License

Java Source Code

package org.davidsingleton.core;
//w w w.  j a  v a 2 s.  com
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.LineNumberReader;

import org.apache.commons.math3.linear.Array2DRowRealMatrix;
import org.apache.commons.math3.linear.RealMatrix;

/**
 * Implementation of a Neural Network with 1 hidden layer. Layer sizes are
 * arbitrary and are determined by the dimensions of the trained weight matrices
 * theta1 and theta2 used to construct the index.
 */
public class NeuralNetwork {

  private RealMatrix theta1Transpose;
  private RealMatrix theta2Transpose;

  /**
   * Constructor for a new NeuralNetwork.
   * @param theta1 - a RealMatrix containing weights for connections between the input layer and hidden layer.
   * @param theta2 - a RealMatrix containing weights for connections between the hidden layer and output layer.
   */
  public NeuralNetwork(RealMatrix theta1, RealMatrix theta2) {
    this.theta1Transpose = theta1.transpose();
    this.theta2Transpose = theta2.transpose();
  }

  double[] predict(byte[] features) {
    double[] xs = new double[features.length + 1];
    xs[0] = 1.0;
    for (int i = 0; i < features.length; i++) {
      xs[i + 1] = features[i] < 0 ? 256 + (double) features[i]
          : (double) features[i];
    }

    RealMatrix x = new Array2DRowRealMatrix(1, features.length + 1);
    x.setRow(0, xs);

    RealMatrix h1 = sigmoidAddOnes(x.multiply(theta1Transpose));
    RealMatrix h2 = sigmoid(h1.multiply(theta2Transpose));
    double[] out = new double[h2.getColumnDimension()];
    for (int z = 0; z < h2.getColumnDimension(); z++) {
      out[z] = h2.getEntry(0, z);
    }
    return out;
  }

  RealMatrix sigmoid(RealMatrix z) {
    // g = 1.0 ./ (1.0 + exp(-z));
    RealMatrix m = z.copy();
    for (int i = 0; i < m.getRowDimension(); i++) {
      for (int j = 0; j < m.getColumnDimension(); j++) {
        double y = m.getEntry(i, j);
        double g = 1.0 / (1.0 + Math.exp(-y));
        m.setEntry(i, j, g);
      }
    }
    return m;
  }

  RealMatrix sigmoidAddOnes(RealMatrix z) {
    // g = 1.0 ./ (1.0 + exp(-z));
    RealMatrix m = new Array2DRowRealMatrix(z.getRowDimension(),
        z.getColumnDimension() + 1);
    for (int i = 0; i < m.getRowDimension(); i++) {
      for (int j = 0; j < m.getColumnDimension(); j++) {
        double g = 1.0;
        if (j != 0) {
          double y = z.getEntry(i, j - 1);
          g = 1.0 / (1.0 + Math.exp(-y));
        }
        m.setEntry(i, j, g);
      }
    }
    return m;
  }

  public static RealMatrix loadMatrixFromOctaveDatFile(String filename) {
    /*
     * Example file format: # Created by Octave 3.4.0, Mon Nov 21 21:47:56 2011
     * GMT <foo@foo> # name: Theta1 # type: matrix # rows: 8 # columns: 25349
     * -0.1138064731504729 -0.0001669091035754908 3.817117905771809e-05 ...
     */
    RealMatrix result = null;
    LineNumberReader lnr = null;
    try {
      FileReader fr = new FileReader(filename);
      lnr = new LineNumberReader(fr);
      int rows = -1;
      int cols = -1;
      boolean created = false;
      String line;
      int rowc = 0;
      int colc = 0;
      while (true) {
        line = lnr.readLine();
        if (line == null) {
          break;
        }
        if (line.startsWith("#")) {
          String[] tokens = line.split(" ");
          if (tokens[1].equals("rows:")) {
            rows = Integer.parseInt(tokens[2]);
          }
          if (tokens[1].equals("columns:")) {
            cols = Integer.parseInt(tokens[2]);
          }

          if (rows > 0 && cols > 0 && !created) {
            result = new Array2DRowRealMatrix(rows, cols);
            created = true;
          }
        } else {
          if (!created) {
            System.err.println("Unexpected non-header read at line "
                + lnr.getLineNumber() + ":" + filename);
            throw new IOException("Invalid file format");
          }
          String[] tokens = line.split(" ");
          for (String token : tokens) {
            if (token.equals("")) {
              continue;
            }
            double d = Double.parseDouble(token);
            result.setEntry(rowc, colc, d);
            colc++;
          }
          rowc++;
          colc = 0;
        }
      }

    } catch (FileNotFoundException e) {
      e.printStackTrace();
    } catch (IOException e) {
      // End of file
    } catch (NumberFormatException e) {
      System.err.println("NumberFormatException reading line "
          + lnr.getLineNumber() + " of " + filename);
      e.printStackTrace();
    }
    return result;
  }
}

Java Source Code List

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