Relevel Factor Variables by Reference

Internal helper function to relevel specified factor variables in a data frame using user-defined reference values.

Usage

.relevel_by_reference(df, reference_values)

Arguments

df

A data frame containing the variables to be releveled.

reference_values

A named list specifying the desired reference level for each variable. Names should match column names in `df`; values should be valid levels.

Value

The original data frame with specified factor variables releveled to the given reference. If a variable is not found in the data frame, a warning is issued and the variable is skipped.

Details

This function is typically used before modeling to ensure that categorical variables have the appropriate reference level, particularly when computing contrasts in regression models.

Examples

if (FALSE) { # \dontrun{
df <- data.frame(group = factor(c("A", "B", "A", "C")))
ref_vals <- list(group = "B")
df <- .relevel_by_reference(df, ref_vals)
levels(df$group)  # "B" will now be the reference level
} # }