surveillance_pop_weighted_incid

[Hanmeng-Xu]

#' @name pop_weighted_admin_mean_incid
#' @title pop_weighted_admin_mean_incid
#' @description pop_weighted_admin_mean_incid
#' @param datapath path to input data
#' @param modelpath
#' @param incidence_rate_raster
#' @param pop_raster
#' @param country
#' @param admin_shp
#' @return
#' @export
#' @include

1. pop_raster and incidence_rate_raster should have the same extent;
2. pop_for_weights and the incidence_rate_raster should have the same resolution;
3. incidence rate in each admin should be between the max and min of the incidence rate within the shp of that admin.