Merge

Summary

Creates a raster object by merging a list of rasters spatially or across dimensions.

Discussion

Use the Merge function to merge multiple raster datasets spatially, across variables, or across dimensions.

The function creates a raster object from the merged datasets.

If the input rasters are not multidimensional, they will be merged spatially. If the input rasters are multidimensional and contain different variables, the function will return a multidimensional raster object with all the variables. If the input rasters are multidimensional and contain different dimension values, the function will return a multidimensional raster object with all the dimension values.

Syntax

Merge(rasters, {resolve_overlap})

Parameter	Explanation	Data Type
rasters	The list of input rasters.	Raster
resolve_overlap	The method used to handle overlapping pixels when merging rasters spatially or dimensionally. FIRST—The pixel value will be determined by the raster that appears first in the list of rasters. This is the default. LAST—The pixel value will be determined by the raster that appears last in the list of rasters. MIN—The pixel value will be determined by the lowest pixel value in the overlapping rasters. MAX—The pixel value will be determined by the highest pixel value in the overlapping rasters. MEAN—The pixel value will be determined by the average of the overlapping pixel values. SUM—The pixel value will be determined by the sum of the overlapping pixel values. The default value is FIRST.	String

Parameter

Explanation

Data Type

rasters

The list of input rasters.

Raster

resolve_overlap

The method used to handle overlapping pixels when merging rasters spatially or dimensionally.

FIRST—The pixel value will be determined by the raster that appears first in the list of rasters. This is the default.
LAST—The pixel value will be determined by the raster that appears last in the list of rasters.
MIN—The pixel value will be determined by the lowest pixel value in the overlapping rasters.
MAX—The pixel value will be determined by the highest pixel value in the overlapping rasters.
MEAN—The pixel value will be determined by the average of the overlapping pixel values.
SUM—The pixel value will be determined by the sum of the overlapping pixel values.

The default value is FIRST.

String

Return value

Data Type	Explanation
Raster	The output merged raster object.

Code sample

Merge example 1

Merges three land cover raster datasets spatially into a single raster.

import arcpy
from arcpy.ia import *

# Set input rasters
in_raster1 = arcpy.Raster("Canada_landcover.tif")
in_raster2 = arcpy.Raster("USA_landcover.tif")
in_raster3 = arcpy.Raster("Mexico_landcover.tif")

# Merge the three rasters
NorthAmericaLC = arcpy.ia.Merge([in_raster1, in_raster2, in_raster3], "FIRST")
NorthAmericaLC.save("NorthAmerica_landcover.tif")

Merge example 2

Merges two multidimensional raster datasets with different variables into a single multidimensional raster with two variables.

import arcpy
from arcpy.ia import *

# Set input multidimensional rasters
# multidim_1 contains a precipitation variable, measured daily in 2018
# multidim_2 contains a temperature variable, measured daily in 2018
multidim_1 = arcpy.Raster("prcp_daily_2018.nc", True)
multidim_2 = arcpy.Raster("temp_daily_2018.nc", True)

# Merge the two multidimensional rasters
multidim_precip_temp = arcpy.ia.Merge([multidim_1, multidim_2])

# The result contains both daily variables for the year 2018
multidim_precip_temp.save("prcp_and_temp_2018.crf")

Merge example 3

Merges two multidimensional raster datasets with different dimension values into a single multidimensional raster with two years of data.

import arcpy
from arcpy.ia import *

# Set input multidimensional rasters
# multidim_1 contains a precipitation variable, measured daily in 2017
# multidim_2 contains a temperature variable, measured daily in 2018
multidim_1 = arcpy.Raster("precip_daily_2017.nc", True)
multidim_2 = arcpy.Raster("precip_daily_2018.nc", True)

# Merge the two multidimensional rasters
multidim_precip_17_18 = arcpy.ia.Merge([multidim_1, multidim_2])

# The result contains precipitation variables for the years 2017 and 2018
multidim_precip_17_18.save("prcp_2017_and_2018.crf")