Available with Spatial Analyst license.
Available with 3D Analyst license.
Summary
Creates a raster by looking up values in another field in the table of the input raster.
Illustration
Usage
Both numeric (integer or floating point) or string field types are supported. If the field is integer or string, the output will be an integer raster; otherwise, the output raster will be a floating-point raster.
If the lookup field is of integer type, the values of that field will be written to the output raster attribute table as Value. Other items in the input raster attribute table will not be transferred to the output raster attribute table.
For example, an attribute table of input raster with numeric field Attr1
Value Count Attr1 1 294 1 2 345 8 3 654 3
Output attribute table from Lookup on Attr1 field
Value Count 1 294 3 654 8 345
If the lookup field is a string type, the lookup field will appear in the output raster attribute table, and the value field will be the same numeric type as for input raster. Any other items in the input raster's attribute table will not be transferred to the output raster's attribute table.
For example, consider the attribute table of an input raster with string field Text1
Value Count Attr1 Text1 1 294 1 A 2 6218 8 B 3 28 3 4 3603 9 3
The attribute table of the output raster from running Lookup on the Text1 field would be
Value Count Text1 1 294 A 2 6218 B 3 28 4 3603 3
See Analysis environments and Spatial Analyst for additional details on the geoprocessing environments that apply to this tool.
Syntax
Lookup(in_raster, lookup_field)
Parameter | Explanation | Data Type |
in_raster | The input raster that contains a field from which to create a new raster. | Raster Layer |
lookup_field | Field containing the desired values for the new raster. It can be a numeric or string type. | Field |
Return Value
Name | Explanation | Data Type |
out_raster | The output raster whose values are determined by the specified field of the input raster. | Raster |
Code sample
This example creates a new raster determined by the specified field of the input raster.
import arcpy
from arcpy import env
from arcpy.sa import *
env.workspace = "C:/sapyexamples/data"
outRaster = Lookup("mycity","land_code")
outRaster.save("C:/sapyexamples/output/mylandcode.img")
This example creates a new raster determined by the specified field of the input raster.
# Name: lookup_example02.py
# Description: Creates a new raster by looking up values found in another
# field in the table of the input raster.
# 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
inRaster = "mycity"
lookupField = "land_code"
# Execute Lookup
outRaster = Lookup(inRaster, lookupField)
# Save the output
outRaster.save("C:/sapyexamples/output/mylandcode")
Environments
Licensing information
- Basic: Requires Spatial Analyst or 3D Analyst
- Standard: Requires Spatial Analyst or 3D Analyst
- Advanced: Requires Spatial Analyst or 3D Analyst