The “stan_model” Function in R

• Package: rstan

• Purpose: Compiles Stan model code

• General class: Model compilation

• Required argument(s):

• model_code or file: Stan model code or file containing the Stan model.

• Notable optional arguments:

• model_name: Name for the compiled model.

• verbose: Print compilation information.

• allow_undefined: Allow undefined function calls in the Stan model.

• Example:

• # Load the rstan library
  library(rstan)
  
  # Define the Stan model code
  model_code <- '
  data {
  int<lower=0> N;
  real y[N];
  }
  parameters {
  real mu;
  real<lower=0> sigma;
  }
  model {
  y ~ normal(mu, sigma);
  }
  '
  
  # Compile the Stan model
  model <- stan_model(model_code = model_code)
  
  # Check model details
  print(model)
  
  # Demonstrate model fit
  N = 100
  sampling(model, data = list(N = N, y = rnorm(N, 0, 1)))

• This example demonstrates how to use the “stan_model” function from the rstan package to compile Stan model code. You can provide the Stan model code directly or specify a file containing the code. The compiled model can then be used for Bayesian inference using functions like “sampling” from the same package.