cli_vec: vec-trunc not working

[lgaborini]

With {cli} 3.6.1.
Directly from the examples of cli_vec():

library(cli)

x <- cli_vec(names(mtcars), list("vec-trunc" = 3))
cli_text("Column names: {x}.")
#> Column names: mpg, cyl, disp, …, gear, and carb.

^{Created on 2023-11-24 with reprex v2.0.2}

vec-sep and vec-last are not affected.

[lgaborini]

Closing, I thought vec-trunc would set the maximum number of visible items.
I should sleep more.

[DanChaltiel]

It is supposed to do that, but somehow the minimal amount is now 5, which is not documented and doesn't make much sense IMHO.

library(cli)
for(i in 3:7){
  x <- cli_vec(names(mtcars), list("vec-trunc"=i))
  cli_text("Column names (max={i}): {x}.")
}
#> Column names (max=3): mpg, cyl, disp, ..., gear, and carb.
#> Column names (max=4): mpg, cyl, disp, ..., gear, and carb.
#> Column names (max=5): mpg, cyl, disp, ..., gear, and carb.
#> Column names (max=6): mpg, cyl, disp, hp, ..., gear, and carb.
#> Column names (max=7): mpg, cyl, disp, hp, drat, ..., gear, and carb.

^{Created on 2024-02-21 with reprex v2.0.2}

Moreover, the documentation of ?cli_vec provides only an example of vec-trunc, with no real insight into what it does, though there is a bit more in https://cli.r-lib.org/reference/inline-markup.html#collapsing-inline-vectors.

I think you should reopen your issue :-)

[DanChaltiel]

Digging in the code, I found that "vec-trunc" is used in inline_collapse(), which will eventually call ansi_collapse().

The current issue is documented (although not justified) in ?ansi_collapse:

trunc Maximum number of elements to show. For style = "head" at least trunc = 1 is used. For style = "both-ends" at least trunc = 5 is used, even if a smaller number is specified.

I guess this limit was set to ensure readability, but I don't understand why not let the user decide what is readable or not...
For instance, in my case, readability is less important than console cluttering, so a limit of 3 or even 2 would have been a very good thing.

Alternatively, you can use "vec-trunc-style" to force the "head" truncation style:

nms <- cli_vec(names(mtcars), list("vec_trunc"=2, "vec-trunc-style"="head"))
cli_text("Column names: {nms}.")

I guess this will be fixed when they update the documentation of ?cli_vec

[gaborcsardi]

See vec-trunc-style at https://cli.r-lib.org/reference/themes.html?q=vec-trunc#supported-properties

library(cli)
x <- cli_vec(names(mtcars), list("vec-trunc" = 3, "vec-trunc-style" = "head"))
cli_text("Column names: {x}.")

Column names: mpg, cyl, disp, ….