fnAggRadRast: Calculate statistics on a nightlight raster that fall within...
In chrisvwn/Rnightlights: Satellite Nightlight Data Extraction

Description Usage Arguments Value Examples

Calculate stats on the radiance of the pixels in a nightlight raster that fall within a polygon and its subpolygons using the raster package. Given a country polygon with subpolygons representing lower admin levels, it will crop and mask the raster to each subpolygon and calculate the total radiance for the polygon and return a vector of total radiances that matches the subpolygons

fnAggRadRast(
  ctryPoly,
  ctryRastCropped,
  nlType,
  configName,
  extension,
  nlStats,
  custPolyPath = NULL
)

`ctryPoly`	The polygon of the admin level/region of interest. In general is a country polygon with sub-regions usually the lowest known admin level as given by the GADM polygons.
`ctryRastCropped`	The raster containing nightlight radiances to sum. Usually will have already be cropped to the country outline
`nlType`	Character vector The nlType to process
`configName`	character the config short name of raster being processed
`extension`	character the extension of raster being processed
`nlStats`	The statistics to calculate
`custPolyPath`	Alternative to GADM. A path to a custom shapefile zip

data.frame of polygon attributes and the calculated stats, one column per nlStat

#read the Kenya polygon downloaded from GADM and load the lowest admin level (ward)
## Not run: 
ctryPoly <- readCtryPolyAdmLayer(ctryCode="KEN",
    Rnightlights:::getCtryShpLowestLyrNames(ctryCodes="KEN"))

# the VIIRS nightlight raster cropped earlier to the country outline
ctryRastCropped <- raster::raster(Rnightlights:::getCtryRasterOutputFnamePath(ctryCode="KEN",
    nlType="VIIRS.M", nlPeriod="201401"))

#calculate the sum of radiances for the wards in Kenya
sumAvgRadRast <- Rnightlights:::fnAggRadRast(ctryPoly=ctryPoly,
    ctryRastCropped=ctryRastCropped, nlType="VIIRS.M", nlStats=c("sum","mean"))

## End(Not run)