R/glmc-utility.r

In glmc: Fitting Generalized Linear Models Subject to Constraints

"glmc.getXlevels" <-
function (Terms, m) 
{
    xvars <- as.character(attr(Terms, "variables"))[-1]
    if ((yvar <- attr(Terms, "response")) > 0) 
        xvars <- xvars[-yvar]
    if (length(xvars) > 0) {
        xlev <- lapply(m[xvars], levels)
        xlev[!sapply(xlev, is.null)]
    }
    else NULL
}