R recipes step_BoxCox 非負數據的 Box-Cox 變換

step_BoxCox(
  recipe,
  ...,
  role = NA,
  trained = FALSE,
  lambdas = NULL,
  limits = c(-5, 5),
  num_unique = 5,
  skip = FALSE,
  id = rand_id("BoxCox")
)

其他單獨的轉換步驟：step_YeoJohnson() , step_bs() , step_harmonic() , step_hyperbolic() , step_inverse() , step_invlogit() , step_logit() , step_log() , step_mutate() , step_ns() , step_percentile() , step_poly() , step_relu() , step_sqrt()

rec <- recipe(~., data = as.data.frame(state.x77))

bc_trans <- step_BoxCox(rec, all_numeric())

bc_estimates <- prep(bc_trans, training = as.data.frame(state.x77))
#> Warning: Non-positive values in selected variable.
#> Warning: No Box-Cox transformation could be estimated for: `Frost`

bc_data <- bake(bc_estimates, as.data.frame(state.x77))

plot(density(state.x77[, "Illiteracy"]), main = "before")

plot(density(bc_data$Illiteracy), main = "after")


tidy(bc_trans, number = 1)
#> # A tibble: 1 × 3
#>   terms         value id          
#>   <chr>         <dbl> <chr>       
#> 1 all_numeric()    NA BoxCox_0O2vM
tidy(bc_estimates, number = 1)
#> # A tibble: 7 × 3
#>   terms          value id          
#>   <chr>          <dbl> <chr>       
#> 1 Population  0.000966 BoxCox_0O2vM
#> 2 Income      0.524    BoxCox_0O2vM
#> 3 Illiteracy -0.379    BoxCox_0O2vM
#> 4 Life Exp    4.59     BoxCox_0O2vM
#> 5 Murder      0.606    BoxCox_0O2vM
#> 6 HS Grad     1.92     BoxCox_0O2vM
#> 7 Area        0.250    BoxCox_0O2vM