R/methods.R

In sdmTMB: Spatial and Spatiotemporal SPDE-Based GLMMs with 'TMB'

#' @import methods
#' @export
summary.sdmTMB <- function(object, ..., digits) {
  print(object, ...)
}

mround <- function(x, digits) {
  sprintf(paste0("%.", digits, "f"), round(x, digits))
}

#' Extract the number of observations of an sdmTMB model
#'
#' @param object The fitted sdmTMB model object
#' @importFrom stats nobs
#' @export
#' @noRd
nobs.sdmTMB <- function(object, ...) {
    sum(!is.na(object$data[all.vars(object$formula[[1]])[1]]))
}

#' Get fitted values from an sdmTMB model
#'
#' @param object The fitted sdmTMB model object
#' @importFrom stats predict
#' @export
#' @noRd
fitted.sdmTMB <- function(object, ...) {

  if (!"offset" %in% names(object))
    cli_abort("It looks like this was fit with an older version of sdmTMB. Try sdmTMB:::update_version(fit).")
  if (isTRUE(object$family$delta)) {
    inv1 <- object$family[[1]]$linkinv
    p <- predict(object, type = "link", offset = object$offset)
    p1 <- inv1(p$est1)
    inv2 <- object$family[[2]]$linkinv
    p2 <- inv2(p$est2)
    p1 * p2
  } else {
    inv <- object$family$linkinv
    inv(predict(object, type = "link", offset = object$offset)$est)
  }
}

#' Get fixed-effect coefficients
#'
#' @param object The fitted sdmTMB model object
#' @param complete Currently ignored
#' @param ... Currently ignored
#' @importFrom stats coef
#' @export
#' @noRd
coef.sdmTMB <- function(object, complete = FALSE, ...) {
  x <- tidy(object)
  out <- x$estimate
  names(out) <- x$term
  out
}

#' Get variance-covariance matrix
#'
#' @param object The fitted sdmTMB model object
#' @param complete Currently ignored
#' @param ... Currently ignored
#' @importFrom stats vcov
#' @export
#' @noRd
vcov.sdmTMB <- function(object, complete = FALSE, ...) {
  sdr <- object$sd_report
  v <- sdr$cov.fixed
  fe <- tidy(object)$term
  nm <- colnames(v)
  i <- grepl("^b_j$", nm)
  if (sum(i)) {
    if (sum(i) == length(fe)) { # should always be true
      nm[i] <- fe
    }
  }
  colnames(v) <- nm
  rownames(v) <- nm
  if (isTRUE(complete)) {
    return(v)
  } else {
    return(v[i,i,drop=FALSE])
  }
}

#' Get CIs
#'
#' @param object The fitted sdmTMB model object
#' @param parm Parameters to return CIs
#' @param level CI level
#' @param ... Ignored
#' @importFrom stats confint
#' @export
#' @noRd
confint.sdmTMB <- function(object, parm, level = 0.95, ...) {
  td <- tidy(object, conf.int = TRUE, conf.level = level)
  x <- matrix(nrow = nrow(td), ncol = 3L)
  x[,3L] <- td$estimate
  x[,2L] <- td$conf.high
  x[,1L] <- td$conf.low
  p <- ((1 - level) / 2) * 100
  pn <- paste(c(p, 100 - p), "%")
  colnames(x) <- c(pn, "Estimate")
  rownames(x) <- td$term
  x
}

#' Extract the log likelihood of a sdmTMB model
#'
#' @param object The fitted sdmTMB model object
#' @importFrom stats logLik
#' @export
#' @noRd
logLik.sdmTMB <- function(object, ...) {
  val <- -object$model$objective
  nobs <- nobs.sdmTMB(object)
  lpb <- names(object$tmb_obj$env$last.par.best)
  ran <- c("omega_s", "epsilon_st", "zeta_s", "b_rw_t", "epsilon_re", "RE", "b_smooth")
  df <- sum(!lpb %in% ran)
  structure(val,
    nobs = nobs, nall = nobs, df = df,
    class = "logLik"
  )
}

#' Extract the AIC of a sdmTMB model
#'
#' @param fit The fitted sdmTMB model
#' @param scale The scale (note used)
#' @param k Penalization parameter, defaults to 2
#' @param ... Anything else
#' @noRd
#'
#' @export
extractAIC.sdmTMB <- function(fit, scale, k = 2, ...) {
  L <- logLik(fit)
  edf <- attr(L, "df")
  return(c(edf, c(-2 * L + k * edf)))
}

#' @importFrom stats family
#' @export
family.sdmTMB <- function (object, ...) {
  if (.has_delta_attr(object)) {
    which_model <- attr(object, "delta_model_predict")
    if (is.na(which_model)) which_model <- 2L # combined; for link
    return(object$family[[which_model]])
  }
  if ("visreg_model" %in% names(object)) {
    return(object$family[[object$visreg_model]])
  } else {
    return(object$family)
  }
}

#' @importFrom nlme fixef
#' @method fixef sdmTMB
#' @export
fixef.sdmTMB <- function(object, ...) {
  .t <- tidy(object, silent = TRUE)
  bhat <- .t$estimate
  names(bhat) <- .t$term
  bhat
}

##' @importFrom nlme ranef
#' @method ranef sdmTMB
#' @export
ranef.sdmTMB <- function(object, ...) {
  .t <- tidy(object, "ran_vals", conf.int = FALSE, silent = TRUE)
  terms <- unlist(lapply(strsplit(.t$term,"_"), getElement, 1))
  est <- .t$estimate
  cond <- list()
  for(i in seq_along(unique(terms))) {
    cond[[unique(terms)[i]]] =
      data.frame("Intercept" = est[which(terms == unique(terms)[i])], stringsAsFactors = FALSE)
  }
  return(list(cond = cond))
}

#' @importFrom stats df.residual
#' @method df.residual sdmTMB
#' @export
df.residual.sdmTMB <- function(object, ...) {
  nobs(object) - length(object$model$par)
}

.has_delta_attr <- function(x) {
  "delta_model_predict" %in% names(attributes(x))
}

#' @export
formula.sdmTMB <- function (x, ...) {
  if (.has_delta_attr(x)) {
    which_model <- attr(x, "delta_model_predict")
    if (!identical(x$formula[[1]], x$formula[[2]]) && is.na(which_model)) {
      cli_abort("Delta component formulas are not the same but ggeffects::ggpredict() is trying to predict on the combined model. For now, predict on one or the other component, or keep the formulas the same, or write your own prediction and plot code.")
    }
    if (is.na(which_model)) which_model <- 1L # combined take 1!?
    return(x$formula[[which_model]])
  }
  if (length(x$formula) > 1L) {
    if ("visreg_model" %in% names(x)) {
      return(x$formula[[x$visreg_model]])
    } else {
      return(x$formula)
    }
  } else {
    return(x$formula[[1]])
  }
}

#' @importFrom stats terms
#' @export
terms.sdmTMB <- function(x, ...) {
  # DELTA FIXME: hardcoded to model 1!
  class(x) <- "glm" # fake
  out <- stats::terms(x)
  out[[1]]
}

#' Calculate effects
#'
#' Used by effects package
#'
#' @inheritParams effects::Effect
#'
#' @importFrom stats formula poisson
#'
#' @return
#' Output from [effects::effect()]. Can then be plotted with with associated
#' `plot()` method.
#'
#' @rawNamespace if(getRversion() >= "3.6.0") {
#'   S3method(effects::Effect, sdmTMB)
#' } else {
#'   export(Effect.sdmTMB)
#' }
#' @examplesIf require("effects", quietly = TRUE)
#' fit <- sdmTMB(present ~ depth_scaled, data = pcod_2011, family = binomial(),
#'   spatial = "off")
#' effects::effect("depth_scaled", fit)
#' plot(effects::effect("depth_scaled", fit))
Effect.sdmTMB <- function(focal.predictors, mod, ...) {
  if (!requireNamespace("effects", quietly = TRUE)) {
    cli_abort("Please install the effects package")
  }

  if (is_delta(mod)) {
    msg <- paste0("Effect() and ggeffects::ggeffect() do not yet work with ",
      "sdmTMB delta/hurdle models. Please use ggeffects::ggpredict() instead.")
    cli_abort(msg)
  }

  vc <- vcov(mod)
  b <- tidy(mod, silent = TRUE)

  dummyfuns <- list(
    variance = function(mu) mu,
    initialize = expression(mustart = y + 0.1),
    dev.resids = function(...) stats::poisson()$dev.res(...)
  )

  fam <- family(mod)

  # from glmmTMB:
  dummyfuns <- list(
    variance = function(mu) mu,
    initialize = expression(mustart <- y + 0.1),
    dev.resids = function(...) poisson()$dev.res(...)
  )
  for (i in names(dummyfuns)) {
    if (is.null(fam[[i]])) fam[[i]] <- dummyfuns[[i]]
  }

  coefs <- b$estimate
  names(coefs) <- b$term
  args <- list(
    call = mod$call,
    coefficients = coefs,
    vcov = vc,
    family = fam,
    # formula = formula(mod) # includes random intercepts...
    formula = remove_s_and_t2(mod$split_formula[[1]]$form_no_bars)
  )
  effects::Effect.default(focal.predictors, mod, ..., sources = args)
}

# get_term_names <- function(model) {
#   .names <- gsub(" ", "", labels(terms(model)))
#   .names
# }

#' @export
model.frame.sdmTMB <- function(formula, ...) {
  as.data.frame(formula$data) # no tibbles!
}