| Operand | Explanation | Data Type |
in_raster_or_constant1 | The input to which values will be added. If one of the input is a raster and the other is a scalar, an output raster is created with the scalar value being added to each cell in the input raster. | Raster Layer | Constant |
in_raster_or_constant2 | The input whose values will be added to the first input. If one of the inputs is a raster and the other is a scalar, an output raster is created with the scalar value being added to each cell in the input raster. | Raster Layer | Constant |
Summary
Adds (sums) the values of two rasters on a cell-by-cell basis.
Illustration
Discussion
When using an operator with a raster input, the result will be a raster. However, if all inputs are numbers, the result is a number.
When there are multiple operators in an expression, the operators are not necessarily run in left-to-right order. The operator with the highest precedence value will be run first. For more information, see the operator precedence table in Work with operators in map algebra. Use parentheses to control the run order.
The order of the input is irrelevant for this operator.
If both input values are integers, the output values will be integers; otherwise, the output will be floating-point values.
Another way to perform the addition operation is a += b, which is an alternative way to write a = a + b.
If both inputs are single-band rasters, or one of the inputs is a constant, the output will be a single-band raster.
If both inputs are multiband rasters, the operator will perform the operation on each band from one input, and the output will be a multiband raster. The number of bands in each multiband input must be the same.
If one of the inputs is a multiband raster and the other input is a constant, the operator will perform the operation against the constant value for each band in the multiband input, and the output will be a multiband raster.
If both inputs are multidimensional rasters with the same number of variables, the operator will perform the operation for all slices with the same dimension value, and the output will be a multidimensional raster. The variables in the inputs must have the same dimensions or a common dimension but no uncommon dimensions.
If both inputs have one variable but different names, set the Match Multidimensional Variable environment to False to perform the operation.
If one of the inputs is a multidimensional raster and the other input is a constant, the operator will perform the operation for all slices for all variables against the constant value, and the output will be a multidimensional raster.
Parameters
Code sample
This sample adds two input rasters.
import arcpy
from arcpy import env
from arcpy.sa import *
env.workspace = "C:/sapyexamples/data"
outPlus = Raster("degs") + Raster("negs")
outPlus.save("C:/sapyexamples/output/outplus.img")This sample adds two input rasters.
# Name: Op_Plus_Ex_02.py
# Description: Adds the values of two rasters on a cell-by-cell basis.
# Requirements: Spatial Analyst Extension
# Import system modules
import arcpy
from arcpy import env
from arcpy.sa import *
# Set environment settings
env.workspace = "C:/sapyexamples/data"
# Set local variables
inRaster1 = Raster("cost")
inRaster2 = Raster("degs")
# Execute Plus
outPlus = inRaster1 + inRaster2
# Save the output
outPlus.save("C:/sapyexamples/output/outplus")