Visualize R Data Structures with Trees

A set of tools for inspecting and understanding R data structures inspired by str(). Includes ast() for visualizing abstract syntax trees, ref() for showing shared references, cst() for showing call stack trees, and obj_size() for computing object sizes.


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lobstr provides tools in the same vein as str(), which allow you to dig into the detail of an object.

Installation

Install the released version of lobstr from CRAN:

install.packages("lobstr")

You can install the development version with:

# install.packages("devtools")
devtools::install_github("r-lib/lobstr")

Example

Abstract syntax trees

ast() draws the abstract syntax tree of R expressions:

ast(a + b + c)
#> █─`+` 
#> ├─█─`+` 
#> │ ├─a 
#> │ └─b 
#> └─c
 
ast(function(x = 1) {
  if (x > 0) print("Hi!")
})
#> █─`function` 
#> ├─█─x = 1 
#> ├─█─`{` 
#> │ └─█─`if` 
#> │   ├─█─`>` 
#> │   │ ├─x 
#> │   │ └─0 
#> │   └─█─print 
#> │     └─"Hi!" 
#> └─<inline srcref>

References

ref() shows hows objects can be shared across data structures by digging into the underlying __ref__erences:

x <- 1:1e6
y <- list(x, x, x)
ref(y)
#> █ [1:0x7fa42b6a9598] <list> 
#> ├─[2:0x7fa428ae7c88] <int> 
#> ├─[2:0x7fa428ae7c88] 
#> └─[2:0x7fa428ae7c88]
 
e <- rlang::env()
e$self <- e
ref(e)
#> █ [1:0x7fa42d981790] <env> 
#> └─self = [1:0x7fa42d981790]

A related tool is obj_size(), which computes the size of an object taking these shared references into account:

obj_size(x)
#> 680 B
obj_size(y)
#> 760 B

Call stack trees

cst() shows how frames on the call stack are connected:

f <- function(x) g(x)
g <- function(x) h(x)
h <- function(x) x
f(cst())
#>     █
#>  1. ├─global::f(cst())
#>  2. │ └─global::g(x)
#>  3. │   └─global::h(x)
#>  4. └─lobstr::cst()

News

lobstr 1.0.1

  • ast() prints scalar integer and complex more accurately (#24)

  • obj_addr() no longer increments the reference count of its input (#25)

  • obj_size() now correctly computes size of ALTREP objects on R 3.5.0 (#32)

Reference manual

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install.packages("lobstr")

1.0.1 by Hadley Wickham, 3 months ago


https://github.com/r-lib/lobstr


Report a bug at https://github.com/r-lib/lobstr/issues


Browse source code at https://github.com/cran/lobstr


Authors: Hadley Wickham [aut, cre] , RStudio [cph]


Documentation:   PDF Manual  


GPL-3 license


Imports crayon, Rcpp, rlang

Suggests covr, pillar, pkgdown, testthat

Linking to Rcpp


See at CRAN