tree: Pretty tree-like object printing

In lobstr: Visualize R Data Structures with Trees

Pretty tree-like object printing

Description

A cleaner and easier to read replacement for str for nested list-like objects

Usage

tree(
  x,
  ...,
  index_unnamed = FALSE,
  max_depth = 10L,
  max_length = 1000L,
  show_environments = TRUE,
  hide_scalar_types = TRUE,
  val_printer = crayon::blue,
  class_printer = crayon::silver,
  show_attributes = FALSE,
  remove_newlines = TRUE,
  tree_chars = box_chars()
)

Arguments

x	A tree like object (list, etc.)
...	Ignored (used to force use of names)
index_unnamed	Should children of containers without names have indices used as stand-in?
max_depth	How far down the tree structure should be printed. E.g. 1 means only direct children of the root element will be shown. Useful for very deep lists.
max_length	How many elements should be printed? This is useful in case you try and print an object with 100,000 items in it.
show_environments	Should environments be treated like normal lists and recursed into?
hide_scalar_types	Should atomic scalars be printed with type and length like vectors? E.g. x <- "a" would be shown as x<char [1]>: "a" instead of x: "a".
val_printer	Function that values get passed to before being drawn to screen. Can be used to color or generally style output.
class_printer	Same as val_printer but for the the class types of non-atomic tree elements.
show_attributes	Should attributes be printed as a child of the list or avoided?
remove_newlines	Should character strings with newlines in them have the newlines removed? Not doing so will mess up the vertical flow of the tree but may be desired for some use-cases if newline structure is important to understanding object state.
tree_chars	List of box characters used to construct tree. Needs elements $h for horizontal bar, $hd for dotted horizontal bar, $v for vertical bar, $vd for dotted vertical bar, $l for l-bend, and $j for junction (or middle child).

Value

console output of structure

Examples

x <- list(
  list(id = "a", val = 2),
  list(
    id = "b",
    val = 1,
    children = list(
      list(id = "b1", val = 2.5),
      list(
        id = "b2",
        val = 8,
        children = list(
          list(id = "b21", val = 4)
        )
      )
    )
  ),
  list(
    id = "c",
    val = 8,
    children = list(
      list(id = "c1"),
      list(id = "c2", val = 1)
    )
  )
)

# Basic usage
tree(x)

# Even cleaner output can be achieved by not printing indices
tree(x, index_unnamed = FALSE)

# Limit depth if object is potentially very large
tree(x, max_depth = 2)

# You can customize how the values and classes are printed if desired
tree(x, val_printer = function(x) {
  paste0("_", x, "_")
})

lobstr documentation built on June 23, 2022, 1:05 a.m.