save x column names from fit_xy()

to close #1166.

This bug happened because we don't know the name of the outcome(s) y when using fit_xy() because it is often a nameless vector. So instead, what I tried to do was to save the names of the x and subset with those when appropriate.

This is NOT a xgboost issue. it is just that xgboost complains more loudly than other engines.

library(parsnip)

spec <- boost_tree() %>%
  set_mode("regression") %>%
  set_engine("xgboost")

lm_fit <- fit(spec, mpg ~ ., data = mtcars)

predict(lm_fit, mtcars)
#> # A tibble: 32 × 1
#>    .pred
#>    <dbl>
#>  1  20.9
#>  2  20.9
#>  3  22.6
#>  4  21.0
#>  5  18.4
#>  6  18.1
#>  7  14.2
#>  8  23.7
#>  9  22.4
#> 10  18.9
#> # ℹ 22 more rows

lm_fit <- fit_xy(spec, x = mtcars[, -1], y = mtcars[, 1])

predict(lm_fit, mtcars)
#> # A tibble: 32 × 1
#>    .pred
#>    <dbl>
#>  1  20.9
#>  2  20.9
#>  3  22.6
#>  4  21.0
#>  5  18.4
#>  6  18.1
#>  7  14.2
#>  8  23.7
#>  9  22.4
#> 10  18.9
#> # ℹ 22 more rows

^{Created on 2024-08-30 with reprex v2.1.0}

tidymodels / parsnip

save x column names from fit_xy() #1168