如何在Infer.NET的BPM中包含更多結果？

Question

如何修改Infer.NET的Tutorial 4: Bayes Point Machine以包含更多結果？

例如，如何添加willRent並獲取willBuy和willRent的單獨概率？

 double[] incomes = { 63, 16, 28, 55, 22, 20 }; 
     double[] ages = { 38, 23, 40, 27, 18, 40 }; 
     bool[] willBuy = { true, false, true, true, false, false }; 
     bool[] willRent = { false, false, true, false, true, false }; 

編輯 - 下面是複製/粘貼格式的例子：

static void Main() 
{ 
    double[] incomes = { 63, 16, 28, 55, 22, 20 }; 
    double[] ages = { 38, 23, 40, 27, 18, 40 }; 
    bool[] willBuy = { true, false, true, true, false, false }; 

    // Create x vector, augmented by 1 
    Vector[] xdata = new Vector[incomes.Length]; 
    for (int i = 0; i < xdata.Length; i++) 
     xdata[i] = Vector.FromArray(incomes[i], ages[i], 1); 
    VariableArray<Vector> x = Variable.Observed(xdata); 

    // Create target y 
    VariableArray<bool> y = Variable.Observed(willBuy, x.Range); 

    Variable<Vector> w = Variable.Random(new VectorGaussian(Vector.Zero(3), PositiveDefiniteMatrix.Identity(3))); 
    Range j = y.Range; 
    double noise = 0.1; 
    y[j] = Variable.GaussianFromMeanAndVariance(Variable.InnerProduct(w, x[j]), noise) > 0; 

    InferenceEngine engine = new InferenceEngine(new ExpectationPropagation()); 
    VectorGaussian wPosterior = engine.Infer<VectorGaussian>(w); 
    Console.WriteLine("Dist over w=\n" + wPosterior); 

    double[] incomesTest = { 58, 18, 22 }; 
    double[] agesTest = { 36, 24, 37 }; 
    VariableArray<bool> ytest = Variable.Array<bool>(new Range(agesTest.Length)); 
    BayesPointMachine(incomesTest, agesTest, Variable.Random(wPosterior), ytest); 
    Console.WriteLine("output=\n" + engine.Infer(ytest)); 

    Console.ReadKey(); 
} 

static void BayesPointMachine(double[] incomes,double[] ages,Variable<Vector> w,VariableArray<bool> y) 
{ 
    // Create x vector, augmented by 1 
    Range j = y.Range; 
    Vector[] xdata = new Vector[incomes.Length]; 
    for (int i = 0; i < xdata.Length; i++) 
     xdata[i] = Vector.FromArray(incomes[i], ages[i], 1); 
    VariableArray<Vector> x = Variable.Observed(xdata, j); 

    // Bayes Point Machine 
    double noise = 0.1; 
    y[j] = Variable.GaussianFromMeanAndVariance(Variable.InnerProduct(w, x[j]), noise) > 0; 
} 

Answer 1

你有4個變量在這裏。

    Will Buy? 
       ^ ^
       /  \ 
       Age  Income 
       \  /
        v  v 
        Will Rent? 

鑑於(Age,Income)，Will Buy和Will Rent是獨立的變量，即，conditional independent。

所以，你可以只構建兩個獨立的貝葉斯點機：

• 一個用於Age，Income和Will Rent。
• 一個用於Age,Income和Will Buy。