reunite_parent_child: Merge two tables that are linked by a foreign key relation

In dm: Relational Data Models

Merge two tables that are linked by a foreign key relation

Description

Perform table fusion by combining two tables by a common (key) column, and then removing this column.

reunite_parent_child(): After joining the two tables by the column id_column, this column will be removed. The transformation is roughly the inverse of what decompose_table() does.

reunite_parent_child_from_list(): After joining the two tables by the column id_column, id_column is removed.

This function is almost exactly the inverse of decompose_table() (the order of the columns is not retained, and the original row names are lost).

Usage

reunite_parent_child(child_table, parent_table, id_column)

reunite_parent_child_from_list(list_of_parent_child_tables, id_column)

Arguments

child_table	Table (possibly created by decompose_table()) that references parent_table
parent_table	Table (possibly created by decompose_table()).
id_column	Identical name of referencing / referenced column in child_table/parent_table.
list_of_parent_child_tables	Cf arguments child_table and parent_table from reunite_parent_child(), but both in a named list (as created by decompose_table()).

Value

A wide table produced by joining the two given tables.

Life cycle

These functions are marked "experimental" because they seem more useful when applied to a table in a dm object. Changing the interface later seems harmless because these functions are most likely used interactively.

See Also

Other table surgery functions: decompose_table()

Examples

decomposed_table <- decompose_table(mtcars, new_id, am, gear, carb)
ct <- decomposed_table$child_table
pt <- decomposed_table$parent_table

reunite_parent_child(ct, pt, new_id)
reunite_parent_child_from_list(decomposed_table, new_id)

dm documentation built on May 29, 2024, 11:41 a.m.