Conditions raised by ggchangepoint

Every error, warning and message this package raises carries a class, so code that calls it can react to the kind of failure rather than matching its wording. The text is written for a person and may be improved between releases; the classes and the fields listed here are the interface, and follow the package's deprecation policy.

Errors

Every error inherits from ggchangepoint_error (and from error and condition). The subclasses, most specific first:

ggchangepoint_input_error

The call itself is not usable: a bad argument or data that violates a precondition. Its subclasses say which precondition: ggchangepoint_short_series (too few observations, for the package or for the engine that was asked; field n), ggchangepoint_wrong_dimension (a univariate method handed a matrix, or the reverse), ggchangepoint_non_finite (NA, NaN or Inf where the method needs finite data), ggchangepoint_bad_type (a factor, text, a survival object or timestamps where a numeric series was expected) and ggchangepoint_bad_argument (an argument value outside its documented range or vocabulary).

ggchangepoint_unsupported

The request is well formed but not something this method offers: a change_in, family or capability the registry does not list for it. Fields method, requested and supported where they apply. Subclasses: ggchangepoint_capability_absent (the result carries no interval, statistic, path or posterior to read), ggchangepoint_planned_method (named in cpt_methods() but not wired) and ggchangepoint_unknown_method.

ggchangepoint_engine_missing

A suggested engine package is not installed. Field package, and install, the call that installs it.

ggchangepoint_engine_error

The upstream engine failed. Fields engine, method and, where it was caught, parent, the engine's own condition.

ggchangepoint_upstream_bug

A known, version-guarded defect in an engine, refused rather than returned. Fields package and version.

ggchangepoint_internal_error

A state the package should never reach: a bug here, worth reporting.

The functions that run many fits (cpt_benchmark(), cpt_consensus()) record a failure that belongs to one method (ggchangepoint_engine_error, ggchangepoint_engine_missing, ggchangepoint_unsupported, ggchangepoint_upstream_bug, or a series of the wrong shape or length for that method) and carry on; any other error stops them, since every method would have hit it.

Warnings

Every warning inherits from ggchangepoint_warning. The ones worth handling by class: ggchangepoint_assumption and its subclasses ggchangepoint_scale_sensitive, ggchangepoint_data_type and ggchangepoint_dependence (the method's assumptions look violated for this series); ggchangepoint_degenerate_segmentation (a changepoint after every observation); ggchangepoint_implausible_count (more changepoints than the series can plausibly hold); ggchangepoint_change_in_routed (the request was answered with the method's native change type); ggchangepoint_argument_ignored; ggchangepoint_level_not_applied; ggchangepoint_selection_unadjusted (p-values computed at data-chosen locations); ggchangepoint_collapsed_ladder; ggchangepoint_replicates_failed; ggchangepoint_cp_dropped (locations normalised away by as_ggcpt()); ggchangepoint_irregular_index; ggchangepoint_na_omitted; ggchangepoint_wide_interval; ggchangepoint_large_fit; ggchangepoint_short_series_warning (a series too short for the result to be interpretable); ggchangepoint_dropped_input (constant coordinates or out-of-range locations left out); ggchangepoint_engine_failed (some methods failed and were left out); ggchangepoint_recycled_input; ggchangepoint_constraint and ggchangepoint_deprecated. Anything else is plain ggchangepoint_warning.

Messages

Informational messages inherit from ggchangepoint_message, so suppressMessages(classes = "ggchangepoint_message") silences this package without silencing the engines.

See also

Other result class: annotate_segments(), as_cpt_series(), as_ggcpt(), as_json(), cpt_annotations(), cpt_export(), cpt_verify(), is_ggcpt(), new_ggcpt(), print.ggcpt()

Examples

res <- tryCatch(cpt_detect(c(1, 2), method = "pelt"),
                ggchangepoint_short_series = function(e) "too short")
res
#> [1] "too short"

# Branch on the kind of failure, not on its wording:
tryCatch(
  cpt_detect(rnorm(50), method = "pelt", change_in = "network"),
  ggchangepoint_unsupported = function(e) {
    paste("unsupported:", e$method, "offers", toString(e$supported))
  }
)
#> [1] "unsupported: pelt offers mean, var, meanvar"