Question

是否无法调试以下错误，或者是否存在任何对应的错误 browser()的功能。当函数sampling()无法创建stanfit对象时，我想在Stan文件中提取转换后的数据块的对象。

failed to create the sampler; sampling not done
Error in new_CppObject_xp(fields$.module, fields$.pointer, ...) : 
  Exception: binomial_rng: Probability parameter is nan, but must be in the interval [0, 1]  (in 'model23b420c17ad_SBC' at line 247)

答复： Stan文件中的功能Print()作为调试器：

使用print（），我们可以打印转换后的数据块中的任何对象，而不管函数rstan::sampling()的结果如何。

m <- rstan::stan_model(model_code = '
                            data{real x;}
                            transformed data{real z; z =  Phi( (-1.14194+ 2.66963)/(-0.257783) );
                                             print("Here, we can use print() as a debugger")
                                             print("")

                                             print("z = ", z)

                            }
                            parameters {real y;}
                            model {y ~ normal(z,1);}
                            generated quantities {real zhat = z;}')
f <- rstan::sampling(m, data=list(x=1), iter = 100,chains=1)
extract(f)[["zhat"]]

作为上述玩具代码的结果，Stan文件中的指定对象在R控制台中的打印如下：

 > f <- rstan::sampling(m, data=list(x=1), iter = 100,chains=1)
Here, we can use print() as a debugger

z = 1.54953e-009

SAMPLING FOR MODEL 'adff65652652045694506de44240c84c' NOW (CHAIN 1).
Chain 1: 
Chain 1: Gradient evaluation took 0 seconds
Chain 1: 1000 transitions using 10 leapfrog steps per transition would take 0 seconds.
Chain 1: Adjust your expectations accordingly!
Chain 1: 
Chain 1: 
Chain 1: WARNING: There aren't enough warmup iterations to fit the
Chain 1:          three stages of adaptation as currently configured.
Chain 1:          Reducing each adaptation stage to 15%/75%/10% of
Chain 1:          the given number of warmup iterations:
Chain 1:            init_buffer = 7
Chain 1:            adapt_window = 38
Chain 1:            term_buffer = 5
Chain 1: 
Chain 1: Iteration:  1 / 100 [  1%]  (Warmup)
Chain 1: Iteration: 10 / 100 [ 10%]  (Warmup)
Chain 1: Iteration: 20 / 100 [ 20%]  (Warmup)
Chain 1: Iteration: 30 / 100 [ 30%]  (Warmup)
Chain 1: Iteration: 40 / 100 [ 40%]  (Warmup)
Chain 1: Iteration: 50 / 100 [ 50%]  (Warmup)
Chain 1: Iteration: 51 / 100 [ 51%]  (Sampling)
Chain 1: Iteration: 60 / 100 [ 60%]  (Sampling)

在“无法创建采样器”时进行调试

0 个答案: