print.data.table {data.table} | R Documentation

## data.table Printing Options

### Description

`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.

### Usage

      ## S3 method for class '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
        quote=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.
`quote` | If `TRUE`, all output will appear in quotes, as in `print.default`.
`...` | Other arguments ultimately passed to `format`.

### Details

By default, with an eye to the typically large number of observations in a codedata.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).

### See Also

`print.default`

### Examples

      #output compression
      DT <- data.table(a = 1:1000)
      print(DT, nrows = 100, topn = 4)

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

      #`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)

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

      #`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)

[Package data.table version 1.12.2 Index]