Document default ranges for tuning parameters

[emmafeuer]

when you run the neighbors() in R, it returns that the default range is [1,10]. Additionally, when you look up the documentation for neighbors(), it says the default is [1,10].

However, when you set neighbors = tune() in a model and try to use the default range, R selects a range of [1, 15] instead of [1, 10]. This can be seen when you run extract_set_parameter_dials() and look at the range.

it would be super helpful to have this discrepancy fixed, either by changing the documentation to be [1, 15] or changing the default that results when you set neighbors = tune()

[EmilHvitfeldt]

Hello @emmafeuer 👋 Thanks for submitting this issue!

What is happening here is the difference between the default dials objects and the model specific dials objects.

You are correct that it has the range 1-10.

library(tidymodels)

neighbors()
#> # Nearest Neighbors (quantitative)
#> Range: [1, 10]

grid_regular(neighbors())
#> # A tibble: 3 × 1
#>   neighbors
#>       <int>
#> 1         1
#> 2         5
#> 3        10

So you could pass dials::parameters(neighbors()) to the param_info argument of tune_grid() and it would use the range [1, 10]` to create the grid.

when you call extract_parameter_set_dials() you extract a parameters object from the model specification. These contain dials objects, but they are allowed to have different defaults the the plain dials objects.

parsnip/R/nearest_neighbor_data.R

Line 18 in dd36a95

func = list(pkg = "dials", fun = "neighbors", range = c(1, 15)),

this is admittedly not documented super well on parsnips side. So if you don't pass anything to param_info or grid in tune_grid() then it will use the model-specific ranges

knn_mod <- nearest_neighbor(neighbors = tune()) |>
  set_mode("classification") |>
  set_engine("kknn")

knn_param_set <- extract_parameter_set_dials(knn_mod) 

knn_param_set$object[[1]]
#> # Nearest Neighbors (quantitative)
#> Range: [1, 15]

grid_regular(knn_param_set)
#> # A tibble: 3 × 1
#>   neighbors
#>       <int>
#> 1         1
#> 2         8
#> 3        15

^{Created on 2023-03-31 with reprex v2.0.2}

[hfrick]

I'm going to move this to parsnip because this is about documenting the default ranges used by parsnip models. The default ranges for (out-of-the-box) dials objects are documented in dials.

[github-actions]

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