"File does not exist" error when running with fixed parameters

[ihuff]

I'm running a prior predictive check and hit a failed assertion when using fixed_param=TRUE with tar_stan_mcmc using targets 1.8.0 and stantargets 0.1.1.900. Reproducible example follows:

targets::tar_dir({
    targets::tar_script({
        library(targets)
        library(stantargets)
        lines <- "data {\n      int <lower = 1> n;\n      vector[n] x;\n      vector[n] y;\n      real true_beta;\n    }\n    parameters {\n      real beta;\n    }\n    model {\n      y ~ normal(x * beta, 1);\n      beta ~ normal(0, 1);\n    }\n    generated quantities {\n      real beta_sim = normal_rng(0, 1);\n      vector[n] y_sim;\n      for (i in 1:n) {\n        y_sim[i] = normal_rng(x[i] * beta, 1);\n      }\n    }"
        writeLines(lines, "x.stan")
        generate_data <- function(n = 10) {
            true_beta <- stats::rnorm(n = 1, mean = 0, sd = 1)
            x <- seq(from = -1, to = 1, length.out = n)
            y <- stats::rnorm(n, x * true_beta, 1)
            list(n = n, x = x, y = y, true_beta = true_beta)
        }
        list(tar_stan_mcmc(example, "x.stan", generate_data(), 
            fixed_param = TRUE, stdout = R.utils::nullfile(), 
            stderr = R.utils::nullfile()))
    })
    targets::tar_make()
})
#> ▶ dispatched target example_data
#> ● completed target example_data [0 seconds, 219 bytes]
#> ▶ dispatched target example_file_x
#> ● completed target example_file_x [0 seconds, 408 bytes]
#> ▶ dispatched target example_mcmc_x
#> ● completed target example_mcmc_x [1.35 minutes, 374.841 kilobytes]
#> ▶ dispatched target example_diagnostics_x
#> ▶ recorded workspace example_diagnostics_x
#> ✖ errored target example_diagnostics_x
#> ✖ errored pipeline [1.354 minutes]
#> 
#> ── General debugging ───────────────────────────────────────────────────────────
#> 
#> ── Debug target example_diagnostics_x ──────────────────────────────────────────
#> 
#> ── How to ──────────────────────────────────────────────────────────────────────
#> 
#> ── Last error message ──────────────────────────────────────────────────────────
#> 
#> ── Last error traceback ────────────────────────────────────────────────────────
#> Error:
#> ! targets::tar_make() error
#>     tar_meta(example_diagnostics_x)$error
#>     tar_workspace(example_diagnostics_x)
#>     • tar_errored()
#>     • tar_meta(fields = any_of("error"), complete_only = TRUE)
#>     • tar_workspace()
#>     • tar_workspaces()
#>     • Debug: https://books.ropensci.org/targets/debugging.html
#>     • Help: https://books.ropensci.org/targets/help.html
#>     Assertion on 'files' failed: File does not exist: 'C:/Users/ihuff/AppData/Local/Temp/Rtmpe0Uv97/x-202411121403-1-96982b.csv'.
#>     tibble::as_tibble(posterior::as_draws_df(example_mcmc_x$sampler_diagnost...
#>     posterior::as_draws_df(example_mcmc_x$sampler_diagnostics())
#>     example_mcmc_x$sampler_diagnostics()
#>     private$read_csv_(variables = "", sampler_diagnostics = NULL,      forma...
#>     read_cmdstan_csv(files = self$output_files(include_failed = FALSE),     ...
#>     assert_file_exists(files, access = "r", extension = "csv")
#>     checkmate::makeAssertion(files, res, .var.name, add)
#>     mstop("Assertion on '%s' failed: %s.", var.name, res, call. = sys.call(-...
#>     stop(simpleError(sprintf(msg, ...), call.))
#>     (function (condition)  {     state$error <- build_message(condition)    ...

^{Created on 2024-11-12 with reprex v2.1.0}

[wlandau]

This is a cmdstanr issue, now posted at stan-dev/cmdstanr#1032. If you set fixed_param = FALSE, it probably does not even make sense to return sampler diagnostics, so you can set return_diagnostics = FALSE in tar_stan_mcmc().