lobstr
lobstr provides tool in the same vein as str()
, tools that allow you
to dig into the detail of an object.
Installation
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)
#> █ [1:0x7f9adf16b078] <list>
#> ├─[2:0x7f9add3d9b48] <int>
#> ├─[2:0x7f9add3d9b48]
#> └─[2:0x7f9add3d9b48]
e <- rlang::env()
e$self <- e
ref(e)
#> █ [1:0x7f9ada2fc7e8] <env>
#> └─self = [1:0x7f9ada2fc7e8]
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())
#> █
#> ├─f(cst())
#> │ └─g(x)
#> │ └─h(x)
#> └─cst()