wi.R

#    Copyright 2020 Australian Institute of Marine Science
#
#    Licensed under the Apache License, Version 2.0 (the "License");
#    you may not use this file except in compliance with the License.
#    You may obtain a copy of the License at
#
#       http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS,
#    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#    See the License for the specific language governing permissions and
#    limitations under the License.

#' wi
#'
#' Calculates model weights based on AIC, AICc, BIC, or DIC
#'
#' @param vec A vector of AIC, AICc, BIC or DIC values
#'
#' @export
#' @return A vector of weights
#'
wi <- function(vec) {
  vals.adj <- vec - min(na.omit(vec))
  wi.den <- rep(NA, length(vals.adj))

  for (i in 1:length(vals.adj)) {
    wi.den[i] <- exp(-1 / 2 * vals.adj[i])
  }
  wi.den.sum <- sum(na.omit(wi.den))
  wi <- wi.den / wi.den.sum
  return(wi)
}