Functions to finalize data-specific parameter ranges

These functions take a parameter object and modify the unknown parts of ranges based on a data set and simple heuristics.

finalize(object, ...)

# S3 method for list
finalize(object, x, force = TRUE, ...)

# S3 method for param
finalize(object, x, force = TRUE, ...)

# S3 method for parameters
finalize(object, x, force = TRUE, ...)

# S3 method for logical
finalize(object, x, force = TRUE, ...)

# S3 method for default
finalize(object, x, force = TRUE, ...)

get_p(object, x, log_vals = FALSE, ...)

get_log_p(object, x, ...)

get_n_frac(object, x, log_vals = FALSE, frac = 1/3, ...)

get_n_frac_range(object, x, log_vals = FALSE, frac = c(1/10, 5/10), ...)

get_n(object, x, log_vals = FALSE, ...)

get_rbf_range(object, x, seed = sample.int(10^5, 1), ...)

get_batch_sizes(object, x, frac = c(1/10, 1/3), ...)

Arguments

object	A param object or a list of param objects.
...	Other arguments to pass to the underlying parameter finalizer functions. For example, for get_rbf_range(), the dots are passed along to kernlab::sigest().
x	The predictor data. In some cases (see below) this should only include numeric data.
force	A single logical that indicates that even if the parameter object is complete, should it update the ranges anyway?
log_vals	A logical: should the ranges be set on the log10 scale?
frac	A double for the fraction of the data to be used for the upper bound. For get_n_frac_range() and get_batch_sizes(), a vector of two fractional values are required.
seed	An integer to control the randomness of the calculations.

Value

An updated param object or a list of updated param objects depending on what is provided in object.

Details

finalize() runs the embedded finalizer function contained in the param object (object$finalize) and returns the updated version. The finalization function is one of the get_*() helpers.

The get_*() helper functions are designed to be used with the pipe and update the parameter object in-place.

get_p() and get_log_p() set the upper value of the range to be the number of columns in the data (on the natural and log10 scale, respectively).

get_n() and get_n_frac() set the upper value to be the number of rows in the data or a fraction of the total number of rows.

get_rbf_range() sets both bounds based on the heuristic defined in kernlab::sigest(). It requires that all columns in x be numeric.

Examples

library(dplyr)
#> 
#> Attaching package: ‘dplyr’
#> The following objects are masked from ‘package:stats’:
#> 
#>     filter, lag
#> The following objects are masked from ‘package:base’:
#> 
#>     intersect, setdiff, setequal, union
car_pred <- select(mtcars, -mpg)

# Needs an upper bound
mtry()
#> # Randomly Selected Predictors (quantitative)
#> Range: [1, ?]
finalize(mtry(), car_pred)
#> # Randomly Selected Predictors (quantitative)
#> Range: [1, 10]

# Nothing to do here since no unknowns
penalty()
#> Amount of Regularization (quantitative)
#> Transformer:  log-10 
#> Range (transformed scale): [-10, 0]
finalize(penalty(), car_pred)
#> Amount of Regularization (quantitative)
#> Transformer:  log-10 
#> Range (transformed scale): [-10, 0]

library(kernlab)
#> 
#> Attaching package: ‘kernlab’
#> The following object is masked from ‘package:scales’:
#> 
#>     alpha
library(tibble)
library(purrr)
#> 
#> Attaching package: ‘purrr’
#> The following object is masked from ‘package:kernlab’:
#> 
#>     cross
#> The following object is masked from ‘package:scales’:
#> 
#>     discard

params <-
  tribble(
     ~parameter,   ~object,
         "mtry",      mtry(),
    "num_terms", num_terms(),
    "rbf_sigma", rbf_sigma()
  )
params
#> # A tibble: 3 x 2
#>   parameter object     
#>   <chr>     <list>     
#> 1 mtry      <nparam[?]>
#> 2 num_terms <nparam[?]>
#> 3 rbf_sigma <nparam[+]>

# Note that `rbf_sigma()` has a default range that does not need to be
# finalized but will be changed if used in the function:
complete_params <-
  params %>%
  mutate(object = map(object, finalize, car_pred))
complete_params
#> # A tibble: 3 x 2
#>   parameter object     
#>   <chr>     <list>     
#> 1 mtry      <nparam[+]>
#> 2 num_terms <nparam[+]>
#> 3 rbf_sigma <nparam[+]>

params %>% dplyr::filter(parameter == "rbf_sigma") %>% pull(object)
#> [[1]]
#> Radial Basis Function sigma (quantitative)
#> Transformer:  log-10 
#> Range (transformed scale): [-10, 0]
#> 
complete_params %>% dplyr::filter(parameter == "rbf_sigma") %>% pull(object)
#> [[1]]
#> Radial Basis Function sigma (quantitative)
#> Transformer:  log-10 
#> Range (transformed scale): [-1.6, -0.933]
#>