data.table Printing Options

print.data.table extends the functionalities of print.data.frame.

Key enhancements include automatic output compression of many observations and concise column-wise class summary.

# S3 method for data.table
print(x,
    topn=getOption("datatable.print.topn"),             # default: 5
    nrows=getOption("datatable.print.nrows"),           # default: 100
    class=getOption("datatable.print.class"),           # default: FALSE
    row.names=getOption("datatable.print.rownames"),    # default: TRUE
    col.names=getOption("datatable.print.colnames"),    # default: "auto"
    print.keys=getOption("datatable.print.keys"),       # default: FALSE
    trunc.cols=getOption("datatable.print.trunc.cols"), # default: FALSE
    quote=FALSE,
    timezone=FALSE, ...)

Arguments

x	A `data.table`.
topn	The number of rows to be printed from the beginning and end of tables with more than `nrows` rows.
nrows	The number of rows which will be printed before truncation is enforced.
class	If `TRUE`, the resulting output will include above each column its storage class (or a self-evident abbreviation thereof).
row.names	If `TRUE`, row indices will be printed alongside `x`.
col.names	One of three flavours for controlling the display of column names in output. `"auto"` includes column names above the data, as well as below the table if `nrow(x) > 20`. `"top"` excludes this lower register when applicable, and `"none"` suppresses column names altogether (as well as column classes if `class = TRUE`.
print.keys	If `TRUE`, any `key` and/or `index` currently assigned to `x` will be printed prior to the preview of the data.
trunc.cols	If `TRUE`, only the columns that can be printed in the console without wrapping the columns to new lines will be printed (similar to `tibbles`).
quote	If `TRUE`, all output will appear in quotes, as in `print.default`.
timezone	If `TRUE`, time columns of class POSIXct or POSIXlt will be printed with their timezones (if attribute is available).
...	Other arguments ultimately passed to `format`.

Details

By default, with an eye to the typically large number of observations in a data.table, only the beginning and end of the object are displayed (specifically, head(x, topn) and tail(x, topn) are displayed unless nrow(x) < nrows, in which case all rows will print).

Examples

  #output compression
  DT <- data.table(a = 1:1000)
  print(DT, nrows = 100, topn = 4)
#>           a
#>       <int>
#>    1:     1
#>    2:     2
#>    3:     3
#>    4:     4
#>   ---      
#>  997:   997
#>  998:   998
#>  999:   999
#> 1000:  1000

  #`quote` can be used to identify whitespace
  DT <- data.table(blanks = c(" 12", " 34"),
                   noblanks = c("12", "34"))
  print(DT, quote = TRUE)
#>    "blanks" "noblanks"
#>    "<char>"   "<char>"
#> 1:    " 12"       "12"
#> 2:    " 34"       "34"

  #`class` provides handy column type summaries at a glance
  DT <- data.table(a = vector("integer", 3),
                   b = vector("complex", 3),
                   c = as.IDate(paste0("2016-02-0", 1:3)))
  print(DT, class = TRUE)
#>        a      b          c
#>    <int> <cplx>     <IDat>
#> 1:     0   0+0i 2016-02-01
#> 2:     0   0+0i 2016-02-02
#> 3:     0   0+0i 2016-02-03

  #`row.names` can be eliminated to save space
  DT <- data.table(a = 1:3)
  print(DT, row.names = FALSE)
#>      a
#>  <int>
#>      1
#>      2
#>      3

  #`print.keys` can alert which columns are currently keys
  DT <- data.table(a=1:3, b=4:6, c=7:9, key="b,a")
  setindexv(DT, c("a", "b"))
  setindexv(DT, "a")
  print(DT, print.keys=TRUE)
#> Key: <b, a>
#> Indices: <a__b>, <a>
#>        a     b     c
#>    <int> <int> <int>
#> 1:     1     4     7
#> 2:     2     5     8
#> 3:     3     6     9

  # `trunc.cols` will make it so only columns that fit in console will be printed
  #    with a message that states the variables not shown
  old_width = options("width" = 40)
  DT <- data.table(thing_11 = vector("integer", 3),
                   thing_21 = vector("complex", 3),
                   thing_31 = as.IDate(paste0("2016-02-0", 1:3)),
                   thing_41 = "aasdfasdfasdfasdfasdfasdfasdfasdfasdfasdf",
                   thing_51 = vector("integer", 3),
                   thing_61 = vector("complex", 3))
  print(DT, trunc.cols=TRUE)
#>    thing_11 thing_21   thing_31
#>       <int>   <cplx>     <IDat>
#> 1:        0     0+0i 2016-02-01
#> 2:        0     0+0i 2016-02-02
#> 3:        0     0+0i 2016-02-03
#> 3 variables not shown: [thing_41 <char>, thing_51 <int>, thing_61 <cplx>]
  options(old_width)

Arguments

Details

See also

Examples

Contents