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Extract per-stratum event times from a formula and data

Source: R/extract_time_to_event.R
extract_time_to_event.Rd

Creates a list of event times that can be passed to downstream visualization or analysis functions such as competing.risk.time or intercurrent.event.time in cifplot() and cifpanel(). Event types are specified by event 1, event 2, censoring, or user-specified codes.

Usage

extract_time_to_event(
  formula,
  data,
  subset.condition = NULL,
  na.action = na.omit,
  which.event = c("event2", "event1", "censor", "censoring", "user_specified"),
  code.event1 = 1,
  code.event2 = 2,
  code.censoring = 0,
  code.user.specified = NULL,
  read.unique.time = TRUE,
  drop.empty = TRUE
)

Arguments

formula

A model formula specifying the outcome and (optionally) strata().

data

A data frame containing variables in formula.

subset.condition

Optional expression (as a character string) defining a subset of data to analyse. Defaults to NULL.

na.action

Function to handle missing values (default: na.omit in stats).

which.event

One of "event1", "event2", "censor", "censoring", or "user_specified", indicating which event type to extract times for.

code.event1, code.event2, code.censoring

Integer codes representing the event and censoring categories. Defaults are 1, 2, and 0, respectively.

code.user.specified

When which.event = "user_specified", the integer event code to extract (e.g., 3 for an intercurrent event).

read.unique.time

Logical if TRUE, only unique and sorted time points are returned for each stratum.

drop.empty

Logical if TRUE (default), strata with no events are dropped from the returned list. Set to FALSE to retain empty strata as numeric(0) vectors (useful for diagnostics or consistent list length).

Value

A named list of numeric vectors, where each element corresponds to a stratum and contains the event times of the selected type.

Details

This function is typically used internally by plotting and model functions, but can also be called directly to inspect the per-stratum event-time structure of a data frame.

Lifecycle

[Stable]

See also

polyreg() for log-odds product modeling of CIFs; cifcurve() for KM/AJ estimators; cifplot() for display of a CIF; cifpanel() for display of multiple CIFs; ggsurvfit::ggsurvfit, patchwork::patchwork and modelsummary::modelsummary for display helpers.

Examples

data(diabetes.complications)
output <- extract_time_to_event(Event(t,epsilon) ~ fruitq,
                                data = diabetes.complications,
                                which.event = "event2")
cifplot(Event(t,epsilon) ~ fruitq,
        data = diabetes.complications,
        outcome.type="competing-risk",
        add.conf=FALSE,
        add.risktable=FALSE,
        add.censor.mark=FALSE,
        add.competing.risk.mark=TRUE,
        competing.risk.time=output,
        label.y="CIF of diabetic retinopathy",
        label.x="Years from registration")