restrict_derivation {admiral}

Execute a Derivation on a Subset of the Input Dataset

Description

Execute a derivation on a subset of the input dataset.

Usage

restrict_derivation(dataset, derivation, args = NULL, filter)

Arguments

dataset

Input dataset

derivation

Derivation

A function that performs a specific derivation is expected. A derivation adds variables or observations to a dataset. The first argument of a derivation must expect a dataset and the derivation must return a dataset. The function must provide the dataset argument and all arguments specified in the params() objects passed to the arg argument.

args

Arguments of the derivation

A params() object is expected.

filter

Filter condition

See Also

params() slice_derivation()

Higher Order Functions: call_derivation(), derivation_slice(), slice_derivation()

Examples

library(tibble)

adlb <- tribble(
  ~USUBJID, ~AVISITN, ~AVAL, ~ABLFL,
  "1",            -1,   113, NA_character_,
  "1",             0,   113, "Y",
  "1",             3,   117, NA_character_,
  "2",             0,    95, "Y",
  "3",             0,   111, "Y",
  "3",             1,   101, NA_character_,
  "3",             2,   123, NA_character_
)

# Derive BASE for post-baseline records only (derive_var_base() can not be used in this case
# as it requires the baseline observation to be in the input dataset)
restrict_derivation(
  adlb,
  derivation = derive_vars_merged,
  args = params(
    by_vars = exprs(USUBJID),
    dataset_add = adlb,
    filter_add = ABLFL == "Y",
    new_vars = exprs(BASE = AVAL)
  ),
  filter = AVISITN > 0
)

# Derive BASE for baseline and post-baseline records only
restrict_derivation(
  adlb,
  derivation = derive_var_base,
  args = params(
    by_vars = exprs(USUBJID)
  ),
  filter = AVISITN >= 0
) %>%
  # Derive CHG for post-baseline records only
  restrict_derivation(
    derivation = derive_var_chg,
    filter = AVISITN > 0
  )