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Changelog

Source: NEWS.md

kofn 0.4.0

Breaking changes

The kofn() constructor now takes a component argument (a dfr_dist prototype from flexhaz) instead of a stringy family argument:

# Before (0.3.x):
kofn(k = 2, m = 3, family = "exponential")
kofn(k = 2, m = 3, family = "weibull")

# After (0.4.0):
kofn(k = 2, m = 3, component = dfr_exponential())
kofn(k = 2, m = 3, component = dfr_weibull())

Rationale: object-based component specification composes with the rest of the ecosystem (flexhaz, serieshaz, maskedhaz) and makes the supported-family table a property of class dispatch rather than a parallel lookup in match.arg. Adding future supported component families is now a one-line change.

The same rename applies to compare_fisher_info():

# Before:
compare_fisher_info(rates = c(1, 2), family = "exponential", ...)

# After:
compare_fisher_info(rates = c(1, 2), component = dfr_exponential(), ...)

Internal helpers parse_params(), kofn_dgp(), and kofn_components() take component rather than family. These were @keywords internal and not part of the public API, but downstream code that touched them via ::: will need the same rename.

New internal helpers

  • n_par_kofn(m, component): expected parameter count for a homogeneous kofn system, replacing inline switch(family, ...) logic.
  • kofn_subclass(component): maps a dfr_dist prototype to the corresponding kofn subclass (exp_kofn or wei_kofn).

Dependencies

  • Added flexhaz (>= 0.5.2) to Imports. The dfr_dist prototype constructors provide family-specific S3 subclasses (dfr_exponential, dfr_weibull) that kofn_subclass() dispatches on.

kofn 0.3.1

Documentation

  • Vignettes restructured around the post-refactor package scope. Deleted outdated vignettes (censoring-framework, kofn-systems, general-kofn, symmetry-breaking) that documented removed topology / general-system APIs; added:
    • getting-started: quick tour of the kofn model, fit, and observation schemes.
    • dist-structure-integration: how kofn delegates DGP and topology to dist.structure, convention conversion, migration notes for v0.2.0 users.
  • Added _pkgdown.yml configuring navbar, article menus, and a reference index grouped by theme.
  • Retained and verified: exponential-parallel, observation-schemes, weibull-em, periodic-inspection, ecosystem.

kofn 0.3.0

Major refactor: dist.structure adoption

kofn now delegates the data-generating process (DGP), topology, and system-level distribution generics to dist.structure. The package focuses exclusively on inference for k-out-of-n systems: log-likelihood, score, Hessian, fit, observation schemes (right/left/interval/periodic), masked cause-of-failure, periodic-inspection (Scheme 1), and Fisher information comparison.

Removed

  • coherent_system(), parallel_system(), series_system(), kofn_system(), bridge_system(), consecutive_k_system(): use the corresponding constructors in dist.structure (coherent_dist, parallel_dist, series_dist, kofn_dist, bridge_dist, consecutive_k_dist).
  • system_signature(), system_lifetime(), system_censoring(), critical_states(), min_paths(), min_cuts(), phi(), min_cuts_from_paths(), minimize_sets(): use dist.structure equivalents (registered on every dist_structure subclass).
  • loglik_system(), fit_system(), rdata_system(): replaced by the loglik/fit/rdata S3 methods on kofn model objects (for k-of-n) plus the dist generics on dist.structure::exp_kofn, wei_kofn, coherent_dist (for general topologies).
  • f_sys_general(), S_sys_general(): use algebraic.dist::density() and surv() on a dist.structure object.
  • make_dists(), exp_dist(), weibull_dist() (the lightweight $pdf/$cdf/$surv list interface): replaced by algebraic.dist::exponential() and weibull_dist() plus the algebraic.dist generics.

Changed

  • kofn() constructor no longer accepts a system = ... argument. kofn is now exclusively for k-of-n estimation. Users with non-k-of-n topologies should use dist.structure::coherent_dist() directly.
  • loglik.exp_kofn and loglik.wei_kofn general-k path now delegates per-observation contributions to dist.structure::exp_kofn(k_dist, par) and wei_kofn(k_dist, shapes, scales) via the algebraic.dist density, surv, and cdf generics. Parallel-fast-path (k=m) IE expansion is preserved as the closed-form path.
  • loglik_scheme1 system density now uses density(dist.structure::exp_kofn(...)) / wei_kofn(...) instead of the local f_sys_general engine.
  • rdata.exp_kofn, rdata.wei_kofn, rdata_masked, rdata_scheme1 use a kofn-internal specialized kofn_censoring(k, times) helper (the k-th order statistic) instead of the general system_censoring algorithm.
  • assumptions.exp_kofn and assumptions.wei_kofn no longer mention “general coherent system” since kofn is k-of-n only.

Internal

  • New file R/internal_topology.R with private helpers kofn_censoring(), kofn_dgp(), kofn_components(). Uses the k_dist = m - k_kofn + 1 conversion between kofn’s :F convention (k_kofn = number of failures triggering system failure) and dist.structure’s :G convention (k_dist = number of functioning components required).
  • Deleted R/coherent_system.R (599 lines), R/system_density.R (336 lines), and R/dist.R (118 lines).
  • Package shrank from 4312 lines to roughly 2750 lines (~36% reduction) in the R/ directory.

Added

  • Imports: dist.structure, algebraic.dist.
  • ncomponents re-exported from dist.structure (was a local generic).

kofn 0.2.0

  • Generalized masking: loglik_masked() and rdata_masked() extend masked cause-of-failure from series (k=1) to arbitrary k-out-of-m systems.

  • Periodic inspection (Scheme 1): loglik_scheme1() and fit_scheme1() support general k via the critical-state density engine.

  • Performance: eagerly precomputed critical/functioning states in coherent_system() and vectorized f_sys_general() give ~70x speedup for Scheme 1 likelihood evaluation.

  • Migrated optimization to the compositional.mle package. The internal helper multistart_mle() was removed and replaced by a private solve_mle() wrapper around compositional.mle::lbfgsb() with a Nelder-Mead fallback in log-parameterization.

  • New vignettes: symmetry-breaking comparison, periodic inspection, observation schemes, general k-out-of-m.

kofn 0.1.0

  • Initial release with exponential and Weibull parallel system MLE.
  • EM algorithm for Weibull parallel systems.
  • Coherent system infrastructure via minimal path/cut sets.
  • Fisher information comparison across observation schemes.