R/weighted_var.R

In James-Thorson/spatial_condition_factor: Package for estimating spatial and spatiotemporal variation in individual condition.

weighted_var <-
function(x, w, na.rm = FALSE) {
  if(na.rm){
    w <- w[i <- !is.na(x)]
    x <- x[i]
  }
  sum.w <- sum(w)
  sum.w2 <- sum(w^2)
  mean.w <- sum(x * w) / sum(w)
  return( (sum.w / (sum.w^2 - sum.w2)) * sum(w * (x - mean.w)^2, na.rm=na.rm) )
}