aggregate.R created

modules/assim.sequential/R/aggregate.R

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+##' @title Aggregation Function
+##' @name aggregate
+##' @author Harunobu Ishii
+##'
+##' @param downscale_output  Raster file output from downscale_function.R. Read file in this way if stored locally: \code{downscale_output <- readRDS("xxx.rds")}
+##' @param polygon_data A spatial polygon object (e.g., an `sf` object) that defines the spatial units for aggregation. 
+##'                     This data should be in a coordinate reference system compatible with the raster data (e.g., "EPSG:4326").
+##'                     Example of state-level aggregation: 
+##'                     \code{
+##'                     us_states <- readRDS("polygon/us_states.rds")
+##'                     state <- "MA"
+##'                     polygon_data <- st_transform(us_states[us_states$STUSPS == state, ], crs = "EPSG:4326")
+##'                     }
+##' @details This function will aggregate previously downscaled carbon flux amount to a spatial unit of choice 
+##'
+##' @return It returns the `polygon_data` with added columns for mean and sum values of the aggregated raster data for each ensemble member.
+
+
+library(exactextractr)
+library(terra)
+library(sf)
+
+aggregate <- function(downscale_output, polygon_data){
+
+    # Perform spatial operations on each raster
+    for (name in names(downscale_output$maps)) {
+      raster_data <- downscale_output$maps[[name]]
+
+      mean_values <- exact_extract(raster_data, polygon_data, fun = 'mean')
+      sum_values <- exact_extract(raster_data, polygon_data, fun = 'sum')
+
+      polygon_data[[paste0(name, "_mean")]] <- mean_values
+      polygon_data[[paste0(name, "_sum")]] <- sum_values
+    }
+return (polygon_data)
+}