R/model_offset_2.R

In linogaliana/gravity: Gravity model with large scale data

# This is a duplication of pscl:::model_offset_2 function
model_offset_2 <- function(x, terms = NULL, offset = TRUE) 
{
  if (is.null(terms)) 
    terms <- attr(x, "terms")
  offsets <- attr(terms, "offset")
  if (length(offsets) > 0) {
    ans <- if (offset) 
      x$"(offset)"
    else NULL
    if (is.null(ans)) 
      ans <- 0
    for (i in offsets) ans <- ans + x[[deparse(attr(terms, 
                                                    "variables")[[i + 1]])]]
    ans
  }
  else {
    ans <- if (offset) 
      x$"(offset)"
    else NULL
  }
  if (!is.null(ans) && !is.numeric(ans)) 
    stop("'offset' must be numeric")
  ans
}