confusing names in tar_map with list of vectors

[ropensci]

confusing names in tar_map with list of vectors

[wlandau]

tar_map() uses static branching, so it does its thing before the pipeline runs. In other words, the label1 target may not even exist yet when tar_map() is called. To define new targets based on the values of upstream targets, you can use dynamic branching.

[wlandau]

I did, but I didn't realize a response from me would be helpful. Substituting vectors of variable length are out of scope for static branching, but it sounds like you found something that works for you. The underlying mechanism is substitute(), and it looks the deparsed vectors are being substituted correctly. Seems like you can continue with your workaround.

[wlandau]

values should be a named data frame or list, where columns/elements are atomic vectors or symbol lists. The names argument uses tidyselect to choose among names(values) to create the target names. The values list you created was nested enough that targets did not try to parse it into a set of friendly names. That sort of thing gets tricky if values gets complicated.

Here are examples similar to yours.

targets::tar_script({
  list(
    tarchetypes::tar_map(
      values = list(label1 = c("foo", "bar"), label2 = c("test1", "test2")),
      names = label1,
      targets::tar_target(b, label2)
    )
  )
})
  
targets::tar_manifest()
#> # A tibble: 2 x 3
#>   name  command     pattern
#>   <chr> <chr>       <chr>  
#> 1 b_foo "\"test1\"" <NA>   
#> 2 b_bar "\"test2\"" <NA>

targets::tar_script({
  list(
    tarchetypes::tar_map(
      values = list(label1 = c("foo", "bar"), label2 = c("test1", "test2")),
      names = starts_with("label"),
      targets::tar_target(b, label2)
    )
  )
})

targets::tar_manifest()
#> # A tibble: 2 x 3
#>   name        command     pattern
#>   <chr>       <chr>       <chr>  
#> 1 b_bar_test2 "\"test2\"" <NA>   
#> 2 b_foo_test1 "\"test1\"" <NA>

^{Created on 2021-04-08 by the reprex package (v1.0.0)}

[adamaltmejd]

Thanks for the quick reply and all your amazing work :). The thing is that in my real project I want to specifically map vectors of variable length. In my code its a setting specifying which variables the data set that I work with should be collapsed over (can be many). So I first run the code for a = c("foo", "bar") and then separately for a = c("test"). Your code is creating two separate targets, one for each element in label2.

I read in the help file that as you say values should be a list of vectors/data frame, but as you can see the nested list that I supplied did result in the correct mapping, only naming is wrong. b_foo returns "foo-bar" and b_bar returns "test1-test".

The code below works though:

targets::tar_dir({ # tar_dir() runs code from a temporary directory.
targets::tar_script({
  list(
      tarchetypes::tar_map(
        values = list(a = list(c("foo", "bar"), c("test1"), c(1, 2, 3)), names = c("foo", "test", "integers")),
        names = names,
        targets::tar_target(b, paste(a, collapse = "-"))
      )
  )
})
targets::tar_manifest()
})
  name       command                                        pattern
  <chr>      <chr>                                          <chr>  
1 b_integers "paste(c(1, 2, 3), collapse = \"-\")"          NA     
2 b_test     "paste(\"test1\", collapse = \"-\")"           NA     
3 b_foo      "paste(c(\"foo\", \"bar\"), collapse = \"-\")" NA     

Not sure why it works to supply a vector of names as values and then assign it to names, but not to assign a character vector immediately (as the help page for tar_map says is possible).

[adamaltmejd]

Ping @wlandau, not sure if you saw my reply?

[adamaltmejd]

Great, was thinking if perhaps my solution was perhaps the result of a bug but thats great. Thanks!

[c1au6i0]

targets::tar_script({
list(
tarchetypes::tar_map(
values = list(label1 = c("foo", "bar"), label2 = c("test1", "test2")),
names = label1,
targets::tar_target(b, label2) )
})

In this example that you @wlandau provided, could the element label1 be defined in another single target?
I tried creating the target and referring to it with label1 = rlang::sym("name_target") without success.
Thanks!