Fix variable skeleton with containers

R/utils.R

@@ -780,7 +780,11 @@ create_skeleton <- function(param_metadata, model_variables,
                        names(model_variables$generated_quantities))
   }
   lapply(param_metadata[target_params], function(par_dims) {
-    array(0, dim = ifelse(length(par_dims) == 0, 1, par_dims))
+    if ((length(par_dims) == 0)) {
+      array(0, dim = 1)
+    } else {
+      array(0, dim = par_dims)
+    }
   })
 }
 

tests/testthat/test-model-methods.R

@@ -277,3 +277,36 @@ test_that("Model methods can be initialised for models with no data", {
   expect_no_error(fit <- mod$sample())
   expect_equal(fit$log_prob(5), -12.5)
 })
+
+test_that("Variable skeleton returns correct dimensions for matrices", {
+  skip_if(os_is_wsl())
+
+  stan_file <- write_stan_file("
+  data {
+    int N;
+    int K;
+  }
+  parameters {
+    real x_real;
+    matrix[N,K] x_mat;
+    vector[K] x_vec;
+    row_vector[K] x_rowvec;
+  }
+  model {
+    x_real ~ std_normal();
+  }")
+  mod <- cmdstan_model(stan_file, compile_model_methods = TRUE,
+                      force_recompile = TRUE)
+  fit <- mod$sample(data = list(N = 4, K = 3), chains = 1,
+                    iter_warmup = 1, iter_sampling = 1)
+
+  target_skeleton <- list(
+    x_real = array(0, dim = 1),
+    x_mat = array(0, dim = c(4, 3)),
+    x_vec = array(0, dim = c(3)),
+    x_rowvec = array(0, dim = c(3))
+  )
+
+  expect_equal(fit$variable_skeleton(),
+                target_skeleton)
+})