Let list values in tar_map() keep names

[psychelzh]

The following codes generated a target from tar_map() to extract names from its y values, but in vain. It only returns NULL. Can the named list keep its names?

targets::tar_dir({
  targets::tar_script({
    library(targets)
    library(tarchetypes)
    values <- tibble::tribble(
      ~x, ~y,
      "X", list(a = 1)
    )
    tar_option_set(package = "tidyverse")
    targets <- tar_map(
      values = values,
      names = x,
      tar_target(
        test,
        names(y)
      )
    )
    list(targets)
  })
  targets::tar_make()
  targets::tar_read(test_X)
})
#> * start target test_X
#> * built target test_X
#> * end pipeline: 0.79 seconds
#> NULL

^{Created on 2022-03-31 by the reprex package (v2.0.1)}

Ideally, the above target test_X will return "a" instead.

[psychelzh]

A second test shows that all the names are gone (even in the nested list)! So how to deal with this? Is there a workaround?

targets::tar_dir({
  targets::tar_script({
    library(targets)
    library(tarchetypes)
    values <- tibble::tribble(
      ~x, ~y,
      "X", list(a = list(b = 1))
    )
    tar_option_set(package = "tidyverse")
    targets <- tar_map(
      values = values,
      names = x,
      tar_target(
        test,
        y
      )
    )
    list(targets)
  })
  targets::tar_make()
  targets::tar_read(test_X)
})
#> * start target test_X
#> * built target test_X
#> * end pipeline: 0.8 seconds
#> [[1]]
#> [[1]][[1]]
#> [1] 1

^{Created on 2022-03-31 by the reprex package (v2.0.1)}

[wlandau]

tar_map() works on language objects, so it should work if you write quote(list(a = list(b = 1))) instead of list(a = list(b = 1)).

[psychelzh]

Thanks! It works! But should this behavior be in tar_target_raw()? Now I have no idea how to do this quote()s programmatically, i.e., generating a list of quoted values from existing data.frame values.

[psychelzh]

Eventually made it work by combining rlang::expr_text() and rlang::parse_expr(). Thank you very much!