data.table: tables – R documentation

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tables

Display 'data.table' metadata

Description

Convenience function for concisely summarizing some metadata of all data.tables in memory (or an optionally specified environment).

Usage

tables(mb=TRUE, order.col="NAME", width=80,
       env=parent.frame(), silent=FALSE, index=FALSE)

Arguments

`mb`	`logical`; `TRUE` adds the rough size of each `data.table` in megabytes to the output under column `MB`.
`order.col`	Column name (`character`) by which to sort the output.
`width`	`integer`; number of characters beyond which the output for each of the columns `COLS`, `KEY`, and `INDICES` are truncated.
`env`	An `environment`, typically the `.GlobalEnv` by default, see Details.
`silent`	`logical`; should the output be printed?
`index`	`logical`; if `TRUE`, the column `INDICES` is added to indicate the indices assorted with each object, see `indices`.

Details

Usually tables() is executed at the prompt, where parent.frame() returns .GlobalEnv. tables() may also be useful inside functions where parent.frame() is the local scope of the function; in such a scenario, simply set it to .GlobalEnv to get the same behaviour as at prompt.

Note that on older versions of R, object.size may be slow, so setting mb=FALSE may speed up execution of tables significantly.

Setting silent=TRUE prints nothing; the metadata are returned as a data.table, invisibly, whether silent is TRUE or FALSE.

Value

A data.table containing the information printed.

Examples

DT = data.table(A=1:10, B=letters[1:10])
DT2 = data.table(A=1:10000, ColB=10000:1)
setkey(DT,B)
tables()

data.table

Extension of `data.frame`

v1.14.0

MPL-2.0 | file LICENSE

Authors

Matt Dowle [aut, cre], Arun Srinivasan [aut], Jan Gorecki [ctb], Michael Chirico [ctb], Pasha Stetsenko [ctb], Tom Short [ctb], Steve Lianoglou [ctb], Eduard Antonyan [ctb], Markus Bonsch [ctb], Hugh Parsonage [ctb], Scott Ritchie [ctb], Kun Ren [ctb], Xianying Tan [ctb], Rick Saporta [ctb], Otto Seiskari [ctb], Xianghui Dong [ctb], Michel Lang [ctb], Watal Iwasaki [ctb], Seth Wenchel [ctb], Karl Broman [ctb], Tobias Schmidt [ctb], David Arenburg [ctb], Ethan Smith [ctb], Francois Cocquemas [ctb], Matthieu Gomez [ctb], Philippe Chataignon [ctb], Nello Blaser [ctb], Dmitry Selivanov [ctb], Andrey Riabushenko [ctb], Cheng Lee [ctb], Declan Groves [ctb], Daniel Possenriede [ctb], Felipe Parages [ctb], Denes Toth [ctb], Mus Yaramaz-David [ctb], Ayappan Perumal [ctb], James Sams [ctb], Martin Morgan [ctb], Michael Quinn [ctb], @javrucebo [ctb], @marc-outins [ctb], Roy Storey [ctb], Manish Saraswat [ctb], Morgan Jacob [ctb], Michael Schubmehl [ctb], Davis Vaughan [ctb], Toby Hocking [ctb], Leonardo Silvestri [ctb], Tyson Barrett [ctb], Jim Hester [ctb], Anthony Damico [ctb], Sebastian Freundt [ctb], David Simons [ctb], Elliott Sales de Andrade [ctb], Cole Miller [ctb], Jens Peder Meldgaard [ctb], Vaclav Tlapak [ctb], Kevin Ushey [ctb], Dirk Eddelbuettel [ctb], Ben Schwen [ctb]

Initial release