filter_extreme: Filter the First or Last Observation for Each By Group
In epijim/admiral: ADaM in R Asset Library

Description Usage Arguments Details Value Author(s) Examples

Filters the first or last observation for each by group.

1	filter_extreme(dataset, by_vars = NULL, order, mode, check_type = "warning")

`dataset`	Input dataset The variables specified by the `order` and the `by_vars` parameter are expected.
`by_vars`	Grouping variables Permitted Values: list of variables
`order`	Sort order Within each by group the observations are ordered by the specified order. Permitted Values: list of variables or functions of variables
`mode`	Selection mode (first or last) If `"first"` is specified, the first observation of each by group is included in the output dataset. If `"last"` is specified, the last observation of each by group is included in the output dataset. Permitted Values: `"first"`, `"last"`
`check_type`	Check uniqueness? If `"warning"` or `"error"` is specified, the specified message is issued if the observations of the input dataset are not unique with respect to the by variables and the order. Default: `"none"` Permitted Values: `"none"`, `"warning"`, `"error"`

For each group (with respect to the variables specified for the by_vars parameter) the first or last observation (with respect to the order specified for the order parameter and the mode specified for the mode parameter) is included in the output dataset.

A dataset containing the first or last observation of each by group

Stefan Bundfuss

library(dplyr, warn.conflict = FALSE)
library(admiral.test)
data("ex")

# Select first dose for each patient
ex %>%
  filter_extreme(
    by_vars = vars(USUBJID),
    order = vars(EXSEQ),
    mode = "first"
  ) %>%
  select(USUBJID, EXSEQ)

# Select highest dose for each patient
ex %>%
  filter_extreme(
    by_vars = vars(USUBJID),
    order = vars(EXDOSE),
    mode = "last",
    check_type = "none"
  ) %>%
  select(USUBJID, EXDOSE)