dm_unnest_tbl: Unnest columns from a wrapped table

In dm: Relational Data Models

Unnest columns from a wrapped table

Description

dm_unnest_tbl() target a specific column to unnest from the given table in a given dm. A ptype or a set of keys should be given, not both.

Usage

dm_unnest_tbl(dm, parent_table, col, ptype)

Arguments

dm	A dm.
parent_table	A table in the dm with nested columns.
col	The column to unnest (unquoted).
ptype	A dm, only used to query names of primary and foreign keys.

Details

dm_nest_tbl() is an inverse operation to dm_unnest_tbl() if differences in row and column order are ignored. The opposite is true if referential constraints between both tables are satisfied.

Value

A dm.

See Also

dm_unwrap_tbl(), dm_unpack_tbl(), dm_nest_tbl(), dm_pack_tbl(), dm_wrap_tbl(), dm_examine_constraints(), dm_examine_cardinalities(), dm_ptype().

Examples

airlines_wrapped <-
  dm_nycflights13() %>%
  dm_wrap_tbl(airlines)

# The ptype is required for reconstruction.
# It can be an empty dm, only primary and foreign keys are considered.
ptype <- dm_ptype(dm_nycflights13())

airlines_wrapped %>%
  dm_unnest_tbl(airlines, flights, ptype)

dm documentation built on Nov. 2, 2023, 6:07 p.m.