maxPtsNeighborDistToHalfThresh: Function to test the use of rowcols and lonlats in...

In chrisvwn/Rnightlights: Satellite Nightlight Data Extraction

Description

Function to test the use of rowcols and lonlats in getCtryNlData as input to the nlStats parameter.

Usage

maxPtsNeighborDistToHalfThresh(
  col,
  row,
  lon,
  lat,
  val,
  numPts = 3,
  enablePlot = FALSE
)

Arguments

col	character parameter to tell the package to pass in the colrow values i.e. column and row indices as per the country polygon
row	character parameter to tell the package to pass in the colrow values i.e. column and row indices of non-NA pixels as per the country polygon
lon	character parameter to tell the package to pass in the lonlat values i.e. column and row indices of non-NA pixels as per the country polygon
lat	character parameter to tell the package to pass in the lonlat values i.e. column and row indices of non-NA pixels as per the country polygon
val	character variable which will hold the raster values found in in the raster
numPts	integer The number of top pixels to detect
enablePlot	logical Plot each stage of the iteration showing the pixels surrounding the top pixel as we move farther out till the target pixel is found. Output will be in PDF format.

Details

The function gets the top numPts brightest pixels in a sub-polygon or zone and looks at increasing neighbouring distances looking for the distance to the first pixel that is 1/2 the value of the central pixel.

Examples

## Not run: 
pkgReset();
  system.time(rastGFT92 <-  getCtryNlData(ctryCode = "NGA",
     admLevel = "lowest", nlTypes = "OLS.Y", nlPeriods = "1992",
     removeGasFlaresMethod = "OGP", ignoreMissing=FALSE, 
     nlStats = list("maxPtsNeighborDistToHalfThresh", 
     list(numPts=1, enablePlot=TRUE))))

  pkgOptions(extractMethod="gdal",cropMaskMethod="gdal");
  system.time(gdalGFT92 <-  getCtryNlData(ctryCode = "NGA",
      admLevel = "lowest", nlTypes = "OLS.Y", nlPeriods = "1992",
      removeGasFlaresMethod = "OGP", ignoreMissing=FALSE,
      nlStats = list("maxPtsNeighborDistToHalfThresh", 
      list(numPts=1, enablePlot=TRUE))))

## End(Not run)

chrisvwn/Rnightlights documentation built on Sept. 7, 2021, 1:44 a.m.