dot-get_reference_levels function

Get reference levels from a (possibly set) list of contrasts

Given a list of contrast matrices, if the contrast matrices were explicitly generated via formulas and they have already had their parameters parsed, use the parameters to look up the reference level for each contrast matrix. If the parameters have not been computed (usually because the contrasts are using the defaults) then look up the reference level manually.

.get_reference_levels(contrast_list, list_params = NULL, formulas = NULL)

Arguments

• contrast_list: List of contrasts, does not need to be named
• list_params: Optional list of parameters, see .make_parameters(), if NULL, then the reference level is determined from the contrast matrix directly.
• formulas: Optional list of formulas, needed if params are passed. Used to get the correct environment for evaluating expressions in params. If NULL, then the reference level is determiend from the contrast matrix directly.

Returns

Character vector of reference levels. If a contrast matrix is not specified for row names, the character value will denote the integer index of the row for the reference level (usually 1).