Question

我在调整线性回归模型时遇到麻烦。观察错误消息时，将在转换后的参数的块部分中进行标识。

请参见下面的stan代码结构。

Packages:

library(rstan)
library(bayesplot)

数据：

head(Orange)
cols <- c(colnames(Orange[-1]))
Orange <- Orange[,cols]
str(Orange)

stan中的代码：

看到stan中的块结构遵循推荐的模式，但是我无法确定代码的哪一部分对我来说似乎是错误的。

y = Orange$circumference
x = Orange$age
n = length(y)

regresstan = '
data{
  int n;
  real y[n];
  real x[n];
}

parameters{
  real alpha;
  real beta;
  real sigma;
}

transformed parameters{
    real mu[n];
    mu = alpha + beta*x;
}

model{
  //Priors
  alpha ~ normal(0, 100);
  beta ~ normal(0, 100);
  sigma ~ uniform(0, 100);

  //Likelihood
    y ~ normal(mu, sigma);
}
'

错误：

SYNTAX ERROR, MESSAGE(S) FROM PARSER:
No matches for: 

  real * real[ ]

Available argument signatures for operator*:

  real * real
  vector * real
  row_vector * real
  matrix * real
  row_vector * vector
  vector * row_vector
  matrix * vector
  row_vector * matrix
  matrix * matrix
  real * vector
  real * row_vector
  real * matrix

No matches for: 

  real + ill-formed

Available argument signatures for operator+:

  int + int
  real + real
  vector + vector
  row_vector + row_vector
  matrix + matrix
  vector + real
  row_vector + real
  matrix + real
  real + vector
  real + row_vector
  real + matrix
  +int
  +real
  +vector
  +row_vector
  +matrix

Expression is ill formed.
 error in 'modele28054257a16_a9d23411185fa271b60f20be43062e80' at line 16, column 23
  -------------------------------------------------
    14: transformed parameters{
    15:     real mu[n];
    16:     mu = alpha + beta*x;
                              ^
    17: }
  -------------------------------------------------

Error in stanc(file = file, model_code = model_code, model_name = model_name,  : 
  failed to parse Stan model 'a9d23411185fa271b60f20be43062e80' due to the above error.

Answer 1

错误来自该行上已转换的参数块

mu = alpha + beta*x;

错误是说您不能将实标量乘以实向量（错误real * real[ ]）。您可以通过遍历mu的值来解决此问题

transformed parameters {
  real mu[n];
  for(i in 1:n) {
    mu[i] = alpha + beta * x[i];
  }
}

此问题得以解决，因为您现在有了一个纯标量乘以一个纯标量。

在Stan上调整线性回归的问题

1 个答案: