basis-size.R

#' Extract basis dimension of a smooth
#'
#' @param object A fitted GAM(M). Currently [mgcv::gam()] (and anything that
#' inherits from the `"gam"` class, e.g. [mgcv::bam()]) and [mgcv::gamm()] are
#' supported.
#' @param ... Arguments passed to other methods.
#'
#' @export
#'
#' @examples
#' load_mgcv()
#'
#' df <- data_sim("eg1", n = 200, seed = 1)
#' m <- bam(y ~ s(x0) + s(x1) + s(x2) + s(x3), data = df)
#'
#' basis_size(m)
`basis_size` <- function(object, ...) {
  UseMethod("basis_size")
}

#' @export
#' @rdname basis_size
`basis_size.mgcv.smooth` <- function(object, ...) {
  check_is_mgcv_smooth(object)
  object[["df"]]
}

#' @export
#' @rdname basis_size
`basis_size.gam` <- function(object, ...) {
  dims <- vapply(object$smooth, basis_size, double(1))
  dims <- setNames(dims, smooths(object))
  dims
}

#' @export
#' @rdname basis_size
`basis_size.gamm` <- function(object, ...) {
  basis_size(object$gam)
}