Join two tagged datasets with lineage tracking

Performs a left, inner, full, or right join and records the operation in the session log. The .__lid__ column from x is preserved. A secondary column .__lid_y__ records which rows of y contributed to each output row, enabling full bilateral tracing.

Usage

lg_join(
  x,
  y,
  by,
  type = c("left", "inner", "full", "right"),
  description = NULL
)

Arguments

x, y

lg_df objects.

by

Character vector of join keys, passed to the underlying dplyr::left_join() (etc.) call.

type

Join type: "left" (default), "inner", "full", "right".

description

Character or NULL. Optional description of the join purpose (e.g. "Merge first dose date from EX domain").

Value

An lg_df with the joined result. .__lid_y__ is added to record the contributing row IDs from y.

See also

lg_derive(), lg_filter()

Examples

lg_start()
#> lineager: session started

adsl <- lg_tag(
  data.frame(USUBJID = c("01", "02"), TRT01P = c("Active", "Placebo")),
  dataset_id = "ADSL"
)
#> lineager: tagged 'ADSL' — 2 rows, 2 cols
ex_summary <- lg_tag(
  data.frame(USUBJID = c("01", "02"), EXSTDTC_min = c("2026-01-01", "2026-01-03")),
  dataset_id = "EX_SUMM"
)
#> lineager: tagged 'EX_SUMM' — 2 rows, 2 cols

adsl_ex <- lg_join(adsl, ex_summary, by = "USUBJID",
                   description = "First dose date from EX domain")
#> lineager: [ADSL + EX_SUMM] left join — 2 rows out