sdbuildR 2.0.0

Breaking changes

• stockflow() is now the constructor for stock-and-flow models. Code that used xmile() or the development-only sdbuildR() constructor should call stockflow() instead.

• update() now replaces the old build() workflow for general model edits. For clearer model-building code, use stock(), flow(), constant(), aux()/auxiliary(), lookup(), and custom_func().

• stockflow is now the primary model class. Code that checked for sdbuildR_xmile or sdbuildR should check for stockflow instead.

• simulate() now returns simulate_stockflow objects, ensemble() returns ensemble_stockflow objects, verify() returns verify_stockflow objects, summary() returns summary_stockflow objects, and compare_models() returns compare_stockflow objects.

• sim_settings() now replaces sim_specs(), and meta() now replaces header().

• summary() now runs model diagnostics. Code that used debugger() should call summary() instead.

• dependencies() now replaces find_dependencies().

• export_model(format = "sdbuildR") now replaces get_build_code().

• sim_methods() now replaces solvers().

• custom_func() now replaces macro() for user-defined model functions.

• import_insightmaker() now replaces insightmaker_to_sfm(), and url_to_insightmaker() now replaces url_to_IM().

• ensemble() now uses conditions instead of range. To retain individual simulations, use save_sims = TRUE instead of return_sims = TRUE.

• plot() methods now use show_constants instead of add_constants. For ensemble plots, use which, sim, condition, and label_subplots instead of type, i, j, and j_labels.

• use_julia(nthreads = ) now controls Julia threading. Code that used use_threads() should set the thread count with use_julia() instead.

• Units are no longer supported. This means that unit-specific helpers from 1.x, including u(), convert_u(), drop_u(), model_units(), unit_prefixes(), get_units(), get_regex_units(), and get_regex_time_units(), are no longer available.

New features

• stockflow() creates an empty model or loads a built-in template using a case-insensitive template name.

• stock(), flow(), constant(), aux()/auxiliary(), lookup(), and custom_func() provide typed model-building helpers around update().

• update() now supports bare variable names and R expressions in name, type, eqn, to, from, and source. Strings and programmatic injection with !! remain supported.

• change_name(), change_type(), and discard() provide focused helpers for renaming, changing, and removing model variables.

• sim_settings() gains flexible output controls with save_at, save_n, vars, and save_sims.

• simulate() accepts temporary simulation-setting overrides through ..., using the same arguments as sim_settings().

• ensemble() can run ensembles in R and Julia, vary stocks and constants with conditions, and retain individual simulations with save_sims = TRUE.

• unit_test(), unit_tests(), and verify() add model-level unit tests for expected simulation behavior, including tests under alternative conditions.

• compare_models() compares model structure, equations, simulation settings, and nonlinearity scores across two stockflow models.

• import_desolve() converts deSolve-style ODE models into stockflow models.

• import_insightmaker() imports Insight Maker models from public URLs, .InsightMaker files, and ModelJSON .json files.

• export_model() exports models as sdbuildR reconstruction code, standalone deSolve scripts, or Psychomodels JSON records.

Improvements and fixes

• as.data.frame() methods now support the stockflow, simulate_stockflow, ensemble_stockflow, and verify_stockflow classes.

• dependencies() can now filter dependencies by variable name and type.

• export_plot() now supports the current plot classes and additional graph export options.

• simulate() and Julia code generation now use a faster AST-based R-to-Julia equation translator. Namespaced calls such as base::sum() translate correctly, and unsupported constructs fall back to the previous translator.

• simulate(), compilation, and summary() now use a content-hashed assembly cache. Repeated calls on unchanged models can skip reassembly, and editing one equation only retranslates that equation.

• simulate() now keeps Julia stock derivative positions aligned with the state vector when stocks are added, removed, renamed, or created by changing a variable’s type.

• summary() and code generation now use an internal structural validator to catch inconsistent model layouts before simulation.

• simulate() now removes temporary CSV files created by single Julia simulations.

• textutils is now a required dependency.

sdbuildR 1.0.8

Minor improvements and bug fixes

• Fixed bug in replacing scientifically formatted numbers
• Fixed bug in comparing Julia versions
• Added alias “sigmoid” for logistic function
• Created constructor and validator for class sdbuildR_sim to improve consistency in output

sdbuildR 1.0.7

sdbuildR 1.0.6

• Fixed error in finding Julia installation

• Simulations in Julia are now ensured to stop at exact simulation times, which removes unexpected results created by numerical errors in the solver (using tstops argument in solve())

sdbuildR 1.0.5

sdbuildR 1.0.4

sdbuildR 1.0.3

• Removed automatic installation of Julia packages and instead wrote a separate function for this: install_julia_env(). install_julia_env() is called in .onLoad() ONLY if the custom environmental variable AUTO_INSTALL_JULIA_ENV is “true” and NOT_CRAN is “true”. This is to ensure GitHub workflows have the Julia environment instantiated, but this will not affect users, as they do not have AUTO_INSTALL_JULIA_ENV.

• Added vignette for formalizing Job Demands-Resources (JDR) Theory

• Improved documentation

sdbuildR 1.0.2

sdbuildR 1.0.1

sdbuildR 1.0.0

• Added extensive solver options
• Created Julia package (SystemDynamicsBuildR.jl) to contain sdbuildR Julia code
• Added vignette for support in installing and setting up Julia
• Added obligatory argument times to step, pulse, ramp, and seasonal