Internal helper to apply level collapsing for a single parameter (Q0 or alpha).
Creates new columns with suffix to avoid modifying original factor columns.
Usage
collapse_factor_levels(data, collapse_spec, factors, suffix)
Arguments
- data
A data frame.
- collapse_spec
Named list of factor collapse specifications.
Structure: list(factor_name = list(new_level = c(old_levels), ...)).
- factors
Character vector of factor names in the model.
- suffix
Character suffix for new column names (e.g., "Q0" or "alpha").
Value
A list with:
data: Modified data frame with new collapsed factor columns
new_factor_names: Character vector of new factor column names to use
info: List with original and new levels for each collapsed factor
