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The event object is used to define events as input for the derive_extreme_event() and derive_vars_extreme_event() functions.


  dataset_name = NULL,
  condition = NULL,
  mode = NULL,
  order = NULL,
  set_values_to = NULL,
  keep_source_vars = NULL,
  description = NULL



Dataset name of the dataset to be used as input for the event. The name refers to the dataset specified for source_datasets in derive_extreme_event(). If the argument is not specified, the input dataset (dataset) of derive_extreme_event() is used.

Permitted Values: a character scalar


An unquoted condition for selecting the observations, which will contribute to the extreme event. If the condition contains summary functions like all(), they are evaluated for each by group separately.

Permitted Values: an unquoted condition


If specified, the first or last observation with respect to order is selected for each by group.

Permitted Values: "first", "last", NULL


The specified variables or expressions are used to select the first or last observation if mode is specified.

For handling of NAs in sorting variables see Sort Order.

Permitted Values: list of expressions created by exprs(), e.g., exprs(ADT, desc(AVAL)) or NULL


A named list returned by exprs() defining the variables to be set for the event, e.g. exprs(PARAMCD = "WSP", PARAM = "Worst Sleeping Problems"). The values can be a symbol, a character string, a numeric value, NA or an expression.

Permitted Values: a named list of expressions, e.g., created by exprs()


Variables to keep from the source dataset

The specified variables are kept for the selected observations. The variables specified for by_vars (of derive_extreme_event()) and created by set_values_to are always kept.

Permitted Values: A list of expressions where each element is a symbol or a tidyselect expression, e.g., exprs(VISIT, VISITNUM, starts_with("RS")).


Description of the event

The description does not affect the derivations where the event is used. It is intended for documentation only.

Permitted Values: a character scalar


An object of class event