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Derive new variables with documented derivation

Source: R/derive.R
lg_derive.Rd

Works exactly like dplyr::mutate() but records a derivation description in the session operation log. Use this when computing ADaM analysis variables from SDTM source variables.

Usage

lg_derive(data, ..., description)

Arguments

data

An lg_df from lg_tag().

...

Name-value pairs of derivations, passed to dplyr::mutate().

description

Character. Required. What is being derived and from what source. E.g. "AVAL: numeric conversion of LBORRES; LBSTRESN used where LBORRES is missing or non-numeric".

Value

An lg_df with derived variables added.

See also

lg_filter(), lg_join(), lg_spec()

Examples

lg_start()
#> lineager: session started
lb <- lg_tag(
  data.frame(USUBJID = "01-001", LBORRES = "12.4",
             LBSTRESN = 12.4, stringsAsFactors = FALSE),
  dataset_id = "LB", domain = "LB"
)
#> lineager: tagged 'LB' — 1 rows, 3 cols

lb_derived <- lg_derive(
  lb,
  AVAL = dplyr::coalesce(LBSTRESN, suppressWarnings(as.numeric(LBORRES))),
  description = "AVAL: LBSTRESN; numeric LBORRES where LBSTRESN is missing"
)
#> lineager: [LB] derive — AVAL: LBSTRESN; numeric LBORRES where LBSTRESN is missing