Set the reference level of a factor — set_reference

Relevels a factor so that the selected category becomes the reference (first) level. By default, the reference level is chosen as the level with the largest total weight, for example the largest exposure in an insurance portfolio. Use method = "manual" with reference_level when a specific business category should be the reference level.

Usage

set_reference_level(
  x,
  weight = NULL,
  method = "largest_weight",
  reference_level = NULL
)

Arguments

x: A factor (unordered). Character vectors should be converted to factor before use.
weight: A numeric vector of the same length as x, typically representing exposure or frequency weights. Required when method = "largest_weight".
method: Character. Method used to choose the reference level. Supported methods are "largest_weight" and "manual".
reference_level: Character string with the level to use as reference when method = "manual".

Value

A factor of the same length as x, with the selected reference level set as the first level.

References

Kaas, Rob & Goovaerts, Marc & Dhaene, Jan & Denuit, Michel. (2008). Modern Actuarial Risk Theory: Using R. doi:10.1007/978-3-540-70998-5.

Author

Martin Haringa

Examples

if (FALSE) { # \dontrun{
library(dplyr)
df <- chickwts |>
mutate(across(where(is.character), as.factor)) |>
mutate(across(where(is.factor), ~set_reference_level(., weight)))

set_reference_level(df$feed, method = "manual", reference_level = "casein")
} # }