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Neural Network Demo

Overview

This project is a demo for a Neural Network class. Allows a user to

  • Construct a Neural network of arbitrary number of layers and nodes per layer
  • Set activation functions at the nodes in the network. (Output layer nodes may have different activation functions than hidden layer nodes.)
  • Train a constructed network from a data file
  • Test a trained network against a data file

Note: "main" function is in file NeuralNetworkFramework/NeuralNetworkFramework.cpp

Testing and Verification

This class was tested using the data files in the TrainingData folder using a NN with the following properties:

  • Output layer activation function: NNUtilities::binaryClassifierActivFunc
  • Hidden layer activation function: NNUtilities::sigmoidFunc
  • Learning_Step_Size = 0.001
  • Regularization_Weight = 0.001
  • nodesPerLayer = ({2, 5, 4, 1})

After training with nandData.csv, these settings should get perfect prediction accuracy on nandTestData.csv.

Summary of files and classes in this repository

Folder: CSVReader

CSVReader (class)

  • This folder contains a utility file that reads data from a CSV file and puts it into vector containers
    • Note: expects training data formatted as CSV containing only ',' and newline / blankspace characters
    • Note: Each line represents a combined input and output vector. * For example, an input vector "[0 1 1 0]" that produces output vector "[-1 1]" should be represented by the line: "0,1,1,0,-1,1"*

Folder: NeuralNetworkFramework

NNUtilityFunctions (namespace)

  • Activation functions (linear, sigmoid, binary classifier)
  • Inner Product calculator
  • Parse a training vector into the input and output vectors that are contained within it
  • Random Number Generator from a Normal Distribution (mean 0.0, stddev 1.0)

NeuralNetworkFramework (main)

  • A sample implementation of the NeuralNetwork class.
    • Initializes structure of an NN
    • Sets the activation functions at the output layer and hidden layers
    • Trains the network on a sample data file
    • Tests the network against a test data set file.

NeuralNetwork (class)

  • User access to the neural network occurs through this class.
  • The public members / methods in this class should be enough for full use of the NN.
  • Private access to a vector of NeuralLayers that make up the network

NeuralLayer (class)

  • Private access to a vector of NeuralNodes that make up the layer
  • Feedforward and backpropogation algorithms for prediction and learning from training data
  • Getters and Setters for node values
  • Pointers to neighboring NeuralLayers

NeuralNode (class)

  • Weight vector and bias
  • Activation functions

Folder: TrainingData

  • Contains two data files representing input and output of a NAND gate. 2D input vector, 1D output vector.
    • Example: [0 0] -> [1]; [0 1] -> [1]; [1 0] -> [1]; [1 1] -> [0]
  • nandData.csv contains 80,000 data vectors
  • nandTestData.csv contains 20,000 data vectors.

I've tested trying to mirror this repo on WheelockLab