Select columns

Select columns of your dm using syntax that is similar to dplyr::select().

Usage

dm_select(dm, table, ...)

Arguments

dm

A dm object.

table

A table in the dm.

...

One or more unquoted expressions separated by commas. You can treat variable names as if they were positions, and use expressions like x:y to select the ranges of variables.

Use named arguments, e.g. new_name = old_name, to rename the selected variables.

The arguments in ... are automatically quoted and evaluated in a context where column names represent column positions. They also support unquoting and splicing. See vignette("programming", package = "dplyr") for an introduction to those concepts.

See select helpers for more details, and the examples about tidyselect helpers, such as starts_with(), everything(), ...

Value

An updated dm with the columns of table reduced and/or renamed.

Details

If key columns are renamed, then the meta-information of the dm is updated accordingly. If key columns are removed, then all related relations are dropped as well.

Examples

dm_nycflights13() %>%
  dm_select(airports, code = faa, altitude = alt)
#> ── Metadata ────────────────────────────────────────────────────────────────────
#> Tables: `airlines`, `airports`, `flights`, `planes`, `weather`
#> Columns: 47
#> Primary keys: 4
#> Foreign keys: 4