Would it be useful to work directly with objects of class model_fit, as produced by tidymodels?

[davidkane9]

Consider:

library(tidymodels)
library(marginaleffects)

mod <- linear_reg() |> 
  fit(mpg ~ hp + drat, data = mtcars)

predictions(mod$fit) # works
#> 
#>  Estimate Std. Error     z Pr(>|z|)     S 2.5 % 97.5 %
#>      23.4      0.671 34.89   <0.001 883.6 22.10   24.7
#>      23.4      0.671 34.89   <0.001 883.6 22.10   24.7
#>      24.1      0.720 33.40   <0.001 810.2 22.65   25.5
#>      19.6      0.999 19.59   <0.001 281.4 17.61   21.5
#>      16.5      0.735 22.47   <0.001 369.1 15.09   18.0
#> --- 22 rows omitted. See ?avg_predictions and ?print.marginaleffects --- 
#>      22.7      0.630 35.96   <0.001 938.3 21.42   23.9
#>      16.9      1.668 10.16   <0.001  78.1 13.68   20.2
#>      18.7      0.625 29.97   <0.001 653.3 17.51   20.0
#>      10.1      1.810  5.57   <0.001  25.2  6.53   13.6
#>      24.5      0.787 31.09   <0.001 702.5 22.91   26.0
#> Columns: rowid, estimate, std.error, statistic, p.value, s.value, conf.low, conf.high, mpg, hp, drat 
#> Type:  response

predictions(mod) # fails
#> Error: Unable to extract the data from model of class `_lm`. This can happen in
#>   a variety of cases, such as when a `marginaleffects` package function is
#>   called from inside a user-defined function, or using an `*apply()`-style
#>   operation on a list. Please supply a data frame explicitly via the
#>   `newdata` argument.

^{Created on 2024-08-22 with reprex v2.1.0}

This is all working as it is supposed to. But my students (and me) were expecting marginaleffects functions to work directly on objects produced by fitting tidymodels. Fortunately, I think this functionality would be easy to add by just checking to see if the value passed in for the model argument is of class model_fit. If it is, we just pull out the $fit.

If this seems reasonable, I could submit a PR.

[vincentarelbundock]

@davidkane9 thanks for raising this issue. Makes sense.

I opened a PR with a potential fix, but I have not tested it extensively. If you have time, check it out and let me know if it works as expected.