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

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. Column name (character) by which to sort the output. integer; number of characters beyond which the output for each of the columns COLS, KEY, and INDICES are truncated. An environment, typically the .GlobalEnv by default, see Details. logical; should the output be printed? 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.

## See also

data.table, setkey, ls, objects, object.size

## Examples

DT = data.table(A=1:10, B=letters[1:10])
DT2 = data.table(A=1:10000, ColB=10000:1)
setkey(DT,B)
tables()
#>    NAME   NROW NCOL MB   COLS KEY
#> 1:   DT     10    2  0    A,B   B
#> 2:  DT2 10,000    2  0 A,ColB
#> Total: 0MB