R/gee_datapull.R

In SSA-Statistical-Team-Projects/SAEplus: Package for Geospatial Analysis & Small Area Estimation Post-Diagnostics

#' Pull spatial data from google earth engine (GEE) for a given region on any feature in the google earth engine database
#'
#' @param email A GEE authenticated gmail address
#' @param gee_boundary A shapefile with the boundaries for a specific region/country for which data is to be collected
#' @param gee_polygons A polygon shapefile spanning the region in the gee_boundary file for features will be computed.
#' forms the unit of analysis
#' @param gee_dataname The specific google earth engine collection dataset name (use default as example)
#' see (https://developers.google.com/earth-engine/datasets/) for full name
#' @param gee_image if TRUE, an image rather than an image collection is expected (FALSE by default)
#' @param gee_datestart The starting date for the specific feature of interest
#' @param gee_dateend The ending date for the specific feature of interest
#' @param gee_band The bandname within the gee_dataname selected (see https://developers.google.com/earth-engine/datasets/)
#' @param scale Used in mean region reduction for zonal statistics
#' @param gee_desc The name to be used to name output in google drive as well as local drive
#' @param gdrive_folder Google Drive folder name to be created or uses if already existing to store shapefile output
#' @param ldrive_dsn Full file path (including shapefile name) for local storage of resulting shapefile
#' @param gee_crs Set CRS
#'
#' @return shapefiles to local drive
#'
#' @import rgee reticulate
#'
#' @export




gee_datapull <- function(email = "ifeanyi.edochie@gmail.com",
                         gee_boundary = "users/ifeanyiedochie/gadm36_CMR_0",
                         gee_polygons = "users/ifeanyiedochie/cmr_polypop_boundary",
                         gee_dataname = "NOAA/VIIRS/DNB/MONTHLY_V1/VCMSLCFG",
                         gee_datestart = "2018-01-01",
                         gee_dateend = "2018-01-31",
                         gee_band = "avg_rad",
                         scale = 100,
                         gee_desc = "nighttimelight_cmr",
                         gee_stat = "mean",
                         gdrive_folder = "/SAEplus",
                         ldrive_dsn = "data/cmr_nighttimelight",
                         gee_crs = "EPSG:4326",
                         tileScale = 1) {
  # ee_users()

  # options(gargle_oauth_email = email)
  ee_Initialize(user = email)

  agebs <- ee$FeatureCollection(gee_polygons)
  agebs_boundary <- ee$FeatureCollection(gee_boundary)

  s5p_collect <-
    ee$ImageCollection(gee_dataname)$filterBounds(agebs_boundary)$filterDate(gee_datestart,
                                                                             gee_dateend)$select(gee_band)

  ## compute zonal stats function
  if (gee_stat == "mean") {
    s5p_mean <- s5p_collect$mean()

    s5p_agebs <- s5p_mean$reduceRegions(
      collection             =  agebs,
      reducer                = ee$Reducer$mean(),
      scale                  = scale,
      crs                    = gee_crs,
      tileScale              = tileScale
    )
  } else if (gee_stat == "sum") {
    s5p_sum <- s5p_collect$sum()

    s5p_agebs <- s5p_sum$reduceRegions(
      collection             = agebs,
      reducer                = ee$Reducer$sum(),
      scale                  = scale,
      crs                    = gee_crs,
      tileScale              = tileScale
    )
  } else if (gee_stat == "stdDev") {
    s5p_stddev <- s5p_collect$stdDev()

    s5p_agebs <- s5p_stddev$reduceRegions(
      collection   = agebs,
      reducer      = ee$Reducer$stdDev(),
      scale        = scale,
      crs          = gee_crs,
      tileScale    = tileScale
    )
  } else if (gee_stat == "median") {
    s5p_median <- s5p_collect$median()

    s5p_agebs <- s5p_median$reduceRegions(
      collection  = agebs,
      reducer     = ee$Reducer$median(),
      scale       = scale,
      crs         = gee_crs,
      tileScale   = tileScale
    )
  } else if (gee_stat == "minMax") {
    s5p_minmax <- s5p_collect$minMax()

    s5p_agebs <- s5p_minmax$reduceRegions(
      collection = agebs,
      reducer    = ee$Reducer$minMax(),
      scale      = scale,
      crs        = gee_crs,
      tileScale  = tileScale
    )
  } else {
    return("gee_stat must be specified as sum or mean, please specify accordingly")
  }


  task_drive <- ee_table_to_drive(
    collection  = s5p_agebs,
    description = gee_desc,
    folder      = gdrive_folder,
    fileFormat  = "SHP"
  )

  task_drive$start()

  ee_monitoring(task_drive)

  task_local <- ee_drive_to_local(task = task_drive,
                                  dsn  = ldrive_dsn)
}