r - 在R的for循环中跳过由 `rstan`软件包触发的错误

Question

如标题所述，我想跳过R中for循环中rstan触发的错误，并让循环继续运行。我知道也有类似的建议tryCatch()或try()的答案，例如this。但是，当错误源自循环内的stan时，它们将不起作用。这是一个最小的示例:

library(rstan)

stancode = 'data {
  int<lower=0> J;          // number of schools
  real y[J];               // estimated treatment effects
  real<lower=0> sigma[J];  // s.e. of effect estimates
}
parameters {
  real mu;
  real<lower=0> tau;
  vector[J] eta;
}
transformed parameters {
  vector[J] theta;
  theta = mu + tau * eta;
}
model {
  target += normal_lpdf(eta | 0, 1);
  target += normal_lpdf(y | theta, sigma);
}'

schools_data <- list(
  J = 8,
  y = c(28,  8, -3,  7, -1,  1, 18, 12),
  sigma = c(-15, 10, 16, 11,  9, 11, 10, 18)#Intentionally created a negative value here
)

for (i in 1:3) {
  tryCatch({fit1 <- stan(model_code  = stancode, data = schools_data,
               chains = 1, iter = 1000, refresh = 0)}, error=function(e){})
}

答案不应该固定为负值，而是跳过for循环中的stan错误。谢谢!

Answer 1

我的系统在运行stan代码时遇到了麻烦，但是您尝试了purrr还是safely()或possibly()？

x <- list(1, "d", 3)
purrr::map(x, ~1/.x)
# error in 1/.x: non numeric argument for binary operator
purrr::map(x, safely(~1/.x))
# [[1]]
# [[1]]$result
# [1] 1
#  
# [[1]]$error
# NULL
#  
#  
# [[2]]
# [[2]]$result
# NULL
#  
# [[2]]$error
# <simpleError in 1/.x: non numeric argument for binary operator>
#   
#   
# [[3]]
# [[3]]$result
# [1] 0.3333333
#  
# [[3]]$error
# NULL