Figaro例题

Figaro例题

问题

想象一个游戏，您有一个轮盘和5个面数不同的色子。轮盘有5个概率相等的结果：2、4、8、12、20。在游戏中，首先转动轮转盘，然后滚动面数与结果相同的色子。编写一个Figaro程序表现这个游戏。
a) 计算滚动12面色子的概率
b) 计算掷出数字7的概率
c) 已知掷出的是7，计算滚动的是12面色子的概率
d) 已知滚动的是12面色子，计算掷出数字7的概率

解答

a.figaro.language._
a.figaro.algorithm.factored.VariableEliminationobject main {def main(args: Array[String]): Unit = {val sect = Select(0.2 -> 2, 0.2 -> 4, 0.2 -> 8, 0.2 -> 12, 0.2 -> 20)val run2 = Select(0.5 -> 1, 0.5 -> 2)val run4 = Select(0.25 -> 1, 0.25 -> 2, 0.25 -> 3, 0.25 -> 4)val run8 = Select(0.175 -> 1, 0.2 -> 2, 0.175 -> 3, 0.175 -> 4, 0.175 -> 5, 0.2 -> 6, 0.175 -> 7, 0.175 -> 8)val run12 = Select(0.0833 -> 1, 0.0833 -> 2, 0.0833 -> 3, 0.0833 -> 4, 0.0833 -> 5, 0.0833 -> 6, 0.0833 -> 7, 0.0833 -> 8, 0.0833 -> 9, 0.0833 -> 10, 0.0833 -> 11, 0.0833 -> 12)val run20 = Select(0.05 -> 1, 0.05 -> 2, 0.05 -> 3, 0.05 -> 4, 0.05 -> 5, 0.05 -> 6, 0.05 -> 7, 0.05 -> 8, 0.05 -> 9, 0.05 -> 10, 0.05 -> 11, 0.05 -> 12, 0.05 -> 13, 0.05 -> 14, 0.05 -> 15, 0.05 -> 16, 0.05 -> 17, 0.05 -> 18, 0.05 -> 19, 0.05 -> 20)val resu = Chain(sect, (i: Int) => if (i == 2) run2; else if (i == 4) run4; else if (i == 8) run8; else if (i == 12) run12; else if (i == 20) run20; else run2)println("a) "+VariableElimination.probability(sect, 12))println("b) "+VariableElimination.probability(resu, 7))resu.observe(7)println("c) "+VariableElimination.probability(sect, 12))resu.unobserve()sect.observe(12)println("d) "+VariableElimination.probability(resu, 7))}
}

结果