R/interpret.frfastformula.R

In npregfast: Nonparametric Estimation of Regression Models with Factor-by-Curve Interactions

#' @importFrom stats as.formula terms.formula 

interpret.frfastformula <-
  function(formula, method = "frfast") {
    
    env <- environment(formula) 
    if(inherits(formula, "character"))          
      formula <- as.formula(formula)
    tf <- terms.formula(formula)
    terms <- attr(tf, "term.labels")
    # if(length(grep(":",terms))!=0)  stop("Symbol '*' is not allowed")
    
    nt <- length(terms)
    if(attr(tf, "response") > 0) {     
      ns <- attr(tf, "specials")$frfast - 1 # -1 for the response
      response <- as.character(attr(tf, "variables")[2])
      vtab<-attr(tf,"factors")
    } else {
      ns <- attr(tf, "specials")$frfast
      response <- NULL
    }
    
    II <- list()
    k <- 0
    if(nt) {
      for (i in 1:nt) {
        if (i %in% ns) {
          k = k+1                   
          st <- eval(parse(text = terms[i]), envir = env)
          if(method ==  "frfast" & st$cov[1] != "ONE") {
            stop("The function frfast does not allow for \"by\" variables")
          }
          II[[k]] <- st$cov
          # h[[k]] <- st$h
          # partial[k] <- terms[i]                                                          
        } else {
          k = k+1
          II[[k]]<- c("ONE", terms[i])
          # h[[k]] <- 0
          # partial[k] <- terms[i]
        }
      }           
    }       
    II <- if(length(II)) {
      matrix(unlist(II), nrow = 2)
    } else {
      matrix(0, nrow = 2)
    }       
    res <- list(response = response, II = II,vtab=vtab)
    
    class(res) <- "frfast.formula"
    return(res)
  }