ctl_new_pillar {pillar}

R Documentation

Customize your tibble subclass

Description

Gain full control over the appearance of the pillars of your tibble subclass in its body. These methods are intended for implementers of subclasses of the "tbl" class. Users will rarely need them.

Usage

ctl_new_pillar(controller, x, width, ..., title = NULL)

ctl_new_pillar_list(
  controller,
  x,
  width,
  ...,
  title = NULL,
  first_pillar = NULL
)

Arguments

controller	The object of class "tbl" currently printed.
x	A vector, can also be a data frame, array or matrix. in ctl_new_pillar_list().
width	The available width, can be a vector for multiple tiers. If NULL, compute only the first pillar.
...	These dots are for future extensions and must be empty.
title	The title, derived from the name of the column in the data.
first_pillar	Can be passed to this method if the first pillar for a compound pillar (or the pillar itself for a simple pillar) has been computed already.

Details

ctl_new_pillar() is called to construct pillars for regular (one-dimensional) vectors. The default implementation returns an object constructed with pillar(). Extend this method to tweak pillar components returned from the default implementation. Override this method to completely change the appearance of the pillars.

ctl_new_pillar_list() is called to construct a list of pillars. It also works for compound pillars: columns that are data frames, matrices or arrays. This method is also called to initiate the construction of all pillars in the tibble to be printed. If called for a regular one-dimensional vector, it returns a list of length one. In any case, all pillars in the returned list of pillars represent only the first column in case of compound columns. This ensures that only those pillars that are shown are constructed. To print all columns of a packed data frame, ctl_new_pillar_list() eventually calls itself recursively. Users will only rarely need to override this method if ever.

All components must be of the same height. This restriction may be levied in the future.

Implementations should return NULL if none of the data fits the available width.

Examples

Run examples

# Create pillar objects
ctl_new_pillar(
  palmerpenguins::penguins,
  palmerpenguins::penguins$species[1:3],
  width = 60
)
ctl_new_pillar(
  palmerpenguins::penguins,
  palmerpenguins::penguins$bill_length_mm[1:3],
  width = 60
)

# Packed data frame
ctl_new_pillar_list(
  tibble::tibble(),
  palmerpenguins::penguins,
  width = 60
)

# Packed matrix
ctl_new_pillar_list(tibble::tibble(), matrix(1:6, ncol = 2), width = 60)

# Packed array
ctl_new_pillar_list(tibble::tibble(), Titanic, width = 60)


# Customize output
lines <- function(char = "-") {
  stopifnot(nchar(char) == 1)
  structure(char, class = "lines")
}

format.lines <- function(x, width, ...) {
  paste(rep(x, width), collapse = "")
}

ctl_new_pillar.line_tbl <- function(controller, x, width, ..., title = NULL) {
  out <- NextMethod()
  new_pillar(list(
    title = out$title,
    type = out$type,
    lines = new_pillar_component(list(lines("=")), width = 1),
    data = out$data
  ))
}

vctrs::new_data_frame(
  list(a = 1:3, b = letters[1:3]),
  class = c("line_tbl", "tbl")
)

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