Marshal a formula into options
marshalFormula(formula, data, from = "rhs", type = "vars",
permitted = c("numeric", "factor"), subset = ":", required = FALSE)
the formula
a data frame to marshal the data from
'rhs' or 'lhs', which side of the formula should be marshalled
'vars' or 'terms', the type of the option be marshalled to
the types of data the option permits
a subset of the formula to marshal
whether this marshall is required or not