What triggers a re-fit?

nlmixr2targets builds on targets, which caches every target keyed by a hash of its command, its dependencies, and its inputs. When you call tar_make(), only targets whose hash has changed (directly or transitively) are rebuilt.

For a single tar_nlmixr(name = <name>, ...) call, the four targets generated are:

The single most important property of this layout is that <name>_fit_simple depends only on the structural content of the model. nlmixr_object_simplify() strips parameter labels and the model’s metadata environment before caching, so cosmetic edits to either do not invalidate the expensive estimation step.

Examples of common edits

# Adding a comment, changing a label, or editing meta:
#   only re-runs the cheap `_object_simple` and the final `<name>` target
#   (the relabel/meta-restore step). The expensive `_fit_simple` is reused.

# Changing initial values (`ini({...})`) or the model structure
# (`model({...})`):
#   re-runs everything from `_object_simple` onward.

# Adding/removing a covariate column from the dataset:
#   re-runs `_data_simple` and `_fit_simple`. `_object_simple` is reused
#   if the model didn't change.

# Changing `est` or `control`:
#   re-runs `_fit_simple` and the final target. `_object_simple` and
#   `_data_simple` are reused.

Inspecting and pruning the indirect cache

The simplified-model md5 cache lives under <tar_config_get("store")>/user/nlmixr2/. It is not removed by targets::tar_destroy(), so it can accumulate orphan files over time (e.g. after model iterations).

# Quick inventory: hashes, sizes, last-modified
nlmixr2targets_cache_status()
#>      hash size_bytes               mtime
#> 1 aaaaaa..       1234 2026-05-21 12:00:00
#> 2 bbbbbb..       1567 2026-05-21 13:30:00

# Find orphans (dry run by default)
nlmixr2targets_cache_prune()

# Delete them
nlmixr2targets_cache_prune(dry_run = FALSE)

nlmixr2targets_cache_prune() with no keep argument reads targets::tar_meta() from the current store, finds every built target whose name ends in _object_simple, and treats those hash values as reachable. Anything else in the cache directory is reported (and, with dry_run = FALSE, removed). Pass keep = character() to wipe the cache unconditionally.

tar_outdated() is a quick way to preview what would rerun

If you are about to edit a model and are unsure how invasive the change is, run

targets::tar_outdated()

after the edit but before tar_make(). The list of outdated targets is exactly the set that would re-execute. Three or four entries means _fit_simple is in play; one or two usually means only the cheap relabel/restore step is.