Perceptron.swift

class Perceptron {
    var bias: Double

    // weights[0] is the weight for the bias input
    var weights: [Double]
    
    init(numInputs: Int, bias: Double) {
        self.bias = bias
        
        self.weights = [Double]()
        for _ in 0...numInputs{
            weights.append(1.0 * (randomDouble() - 0.5))
        }
    }
    
    func activate(input: [Double]) -> Int {
        assert(input.count + 1 == weights.count)
        
        var sum = 0.0
        for i in 0..<input.count {
            sum += input[i] * weights[i + 1]
        }
        sum += bias * weights[0]
        return (sum > 0) ? 1 : -1
    }
}