High-Performance Open-Source Archive
The arcpy package, via reticulate, supports Raster math operations. This vignette demonstrates basic usage of arcpy Raster Algebra from R. First, we'll set up a workspace and create some temporary rasters.
library(arcpy)arcpy$env$workspace = tempdir()
arcpy$env$scratchWorkspace = tempdir()
cellSize = 2
outExtent = arcpy$Extent(0, 0, 250, 250)
# Check out the ArcGIS Spatial Analyst extension license
arcpy$CheckOutExtension("Spatial")## [1] "CheckedOut"# Execute CreateConstantRaster
raster1 = arcpy$sa$CreateConstantRaster(12, "FLOAT",
cellSize, outExtent)
raster2 = arcpy$sa$CreateConstantRaster(6, "FLOAT",
cellSize, outExtent)All of the basic mathematical operations are supported. Usage follows the R operator symbology, rather than the Python operator symbology or arcpy operator symbology (e.g., Modulus is achieved using %%, not %, and exponentiation is achieved using ^ rather than pow() or **).
raster3 = raster1 + raster2
arcpy$management$GetRasterProperties(raster3, "MAXIMUM")## <Result '18'>raster3 = raster1 - raster2
arcpy$management$GetRasterProperties(raster3, "MAXIMUM")## <Result '6'>raster3 = raster1 * raster2
arcpy$management$GetRasterProperties(raster3, "MAXIMUM")## <Result '72'>raster3 = raster1 / raster2
arcpy$management$GetRasterProperties(raster3, "MAXIMUM")## <Result '2'>raster3 = raster1 ^ raster2
arcpy$management$GetRasterProperties(raster3, "MAXIMUM")## <Result '2985984'>raster3 = raster1 %/% raster2
arcpy$management$GetRasterProperties(raster3, "MAXIMUM")## <Result '2'>raster3 = -raster1
arcpy$management$GetRasterProperties(raster3, "MAXIMUM")## <Result '-12'># compound statements work too
raster3 = (raster1 / raster2) * (raster2 - 3.0)
arcpy$management$GetRasterProperties(raster3, "MAXIMUM")## <Result '6'>Logical operators, including compound operations, work on rasters too.
raster3 = raster1 > raster2
arcpy$management$GetRasterProperties(raster3, "MAXIMUM")## <Result '1'>raster3 = raster1 < raster2
arcpy$management$GetRasterProperties(raster3, "MAXIMUM")## <Result '0'>raster3 = raster1 != raster2
arcpy$management$GetRasterProperties(raster3, "MAXIMUM")## <Result '1'>raster3 = raster1 == raster2
arcpy$management$GetRasterProperties(raster3, "MAXIMUM")## <Result '0'>raster3 = raster1 >= 12
arcpy$management$GetRasterProperties(raster3, "MAXIMUM")## <Result '1'>raster3 = raster2 <= 6
arcpy$management$GetRasterProperties(raster3, "MAXIMUM")## <Result '1'># compound statements work as expected too
raster3 = (raster1 > 10) & (raster2 > 10)
arcpy$management$GetRasterProperties(raster3, "MAXIMUM")## <Result '0'>raster3 = (raster1 > 10) | (raster2 > 10)
arcpy$management$GetRasterProperties(raster3, "MAXIMUM")## <Result '1'># The not operator works in R too
raster3 = !(raster2 > 10)
arcpy$management$GetRasterProperties(raster3, "MAXIMUM")## <Result '1'># or you can do
raster3 = arcpy$sa$BooleanNot(raster2 > 10)
arcpy$management$GetRasterProperties(raster3, "MAXIMUM")## <Result '1'>
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