// neuron.cpp
// David R. Morrison

#include "neuron.hpp"

// Constructor
Neuron::Neuron(int input_vector_size)
{
    inputVectorSize = input_vector_size;
    // Randomize the weights; add one to factor in bias
    weights = getRandomWeights(inputVectorSize + 1);
}

// Just do a weighted sum of the inputs
double Neuron::evaluateSample(vector<double> inputs)
{
    assert (inputs.size() == inputVectorSize);

    // The first one is the bias -- always has value of 1.0
    double sum = weights[0];

    // Sum up the rest, starting at 1
    for (int j = 1; j < inputVectorSize + 1; ++j)
        sum += weights[j] * inputs[j - 1];

    return sum;
}

// Get the weight at the specified index
double Neuron::getWeight(unsigned int i)
{
    assert(i < inputVectorSize + 1);
    return weights[i];
}

// Change the weight at the specified index by delta
void Neuron::changeWeight(unsigned int i, double delta)
{
    assert(i < inputVectorSize + 1);
    weights[i] += delta;
}

ostream& Neuron::print(ostream& out)
{
    out.precision(4);
    out << "[ ";
    for (int i = 0; i < weights.size(); ++i)
	out << weights[i] << " ";
    out << "]" << endl;
}

ostream& operator<<(ostream& out, Neuron& n)
{
    return n.print(out);
}