dm_wrap_tbl: Wrap dm into a single tibble dm

In dm: Relational Data Models

Wrap dm into a single tibble dm

Description

dm_wrap_tbl() creates a single tibble dm containing the root table enhanced with all the data related to it through the relationships stored in the dm. It runs a sequence of dm_nest_tbl() and dm_pack_tbl() operations on the dm.

Usage

dm_wrap_tbl(dm, root, strict = TRUE, progress = NA)

Arguments

dm	A cycle free dm object.
root	Table to wrap the dm into (unquoted).
strict	Whether to fail for cyclic dms that cannot be wrapped into a single table, if FALSE a partially wrapped dm will be returned.
progress	Whether to display a progress bar, if NA (the default) hide in non-interactive mode, show in interactive mode. Requires the 'progress' package.

Details

dm_wrap_tbl() is an inverse to dm_unwrap_tbl(), i.e., wrapping after unwrapping returns the same information (disregarding row and column order). The opposite is not generally true: since dm_wrap_tbl() keeps only rows related directly or indirectly to rows in the root table. Even if all referential constraints are satisfied, unwrapping after wrapping loses rows in parent tables that don't have a corresponding row in the child table.

This function differs from dm_flatten_to_tbl() and dm_squash_to_tbl() , which always return a single table, and not a dm object.

Value

A dm object.

See Also

dm_unwrap_tbl(), dm_nest_tbl(), dm_examine_constraints(), dm_examine_cardinalities().

Examples

dm_nycflights13() %>%
  dm_wrap_tbl(root = airlines)

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