Reclassify (Spatial Analyst)
Summary
Reclassifies (or changes) the values in a raster.
Usage
-
The input raster must have valid statistics. If the statistics do not exist, they can be created using the Calculate Statistics tool in the Data Management Tools toolbox.
If a range of values is to be reclassed, the ranges should not overlap except at the boundary of two input ranges. Where overlapping occurs, the higher end of the lower input range is inclusive, and the lower end of the higher input range is exclusive.
For example, if two ranges are specified, such as reclassifying values 1 to 5 as 100 and values 5 to 10 as 200, an input value less than or equal to 5 will be assigned the value 100 in the output, and an input value that is larger than 5, such as 5.01, will be assigned to 200.
-
If using the tool dialog box, the remap table can be stored for future use with the Save button. Use the Load button to open the remap tables you created previously with the Save button.
-
It is recommended to only load tables previously saved by the Reclassify tool. The table format is specific and must contain the fields FROM, TO, OUT, and MAPPING.
When the input raster is a layer in the table of contents, the default reclassification table will honor the unique values or classified renderer symbology properties if set on the layer; otherwise, the reclassification table will default to natural breaks with nine classes.
-
Once the remap table of the reclassification has been modified, the values will not be updated if a new input raster is selected. If the reclassification is not suitable for the new raster, a default reclassification can be reinitialized by:
- Editing or selecting a new value for the reclass field
- Restarting the tool
-
This tool has a precision control that manages how decimal places are treated.
-
When using the Reclassify tool as part of a model:
- If the input to the tool is derived data from a tool that isn't already run, the remap parameter in the Reclassify tool will be empty until the preceding tool is run and the model is validated. To avoid this, always run preceding tools before connecting their output variables as input to the Reclassify tool. Alternatively, you can create a custom reclassification table by adding entries.
- If exposing the reclassification table as a model parameter, the reclass field must be exposed as a variable; however, it does not need to be set as a model parameter. If the field is not exposed as a variable, the classify and unique values buttons will be disabled in the model tool dialog box.
-
By default, this tool will take advantage of multi-core processors. The maximum number of cores that can be utilized is limited to 4.
If you wish the tool to use fewer cores, use the parallelProcessingFactor environment setting.
Syntax
| Parameter | Explanation | Data Type |
in_raster |
The input raster to be reclassified. | Raster Layer |
reclass_field |
Field denoting the values that will be reclassified. | Field |
remap |
The Remap object is used to specify how to reclassify values of the input raster. There are two ways to define how the values will be reclassified in the output raster: RemapRange and RemapValue. Either ranges of input values can be assigned to a new output value, or individual values can be assigned to a new output value. The following are the forms of the remap objects.
| Remap |
missing_values (Optional) |
Denotes whether missing values in the reclass table retain their value or get mapped to NoData.
| Boolean |
Return Value
| Name | Explanation | Data Type |
| out_raster |
The output reclassified raster. The output will always be of integer type. | Raster |
Code Sample
The following examples show several ways of reclassifying a raster.
import arcpy
from arcpy import env
from arcpy.sa import *
env.workspace = "C:/sapyexamples/data"
outReclass1 = Reclassify("landuse", "Value",
RemapValue([[1,9],[2,8],[3,1],[4,6],[5,3],[6,3],[7,1]]))
outReclass1.save("C:/sapyexamples/output/landuse_rcls")
outReclass2 = Reclassify("slope_grd", "Value",
RemapRange([[0,10,"NODATA"],[10,20,1],[20,30,2],
[30,40,3],[40,50,4],[50,60,5],[60,75,6]]))
outReclass2.save("C:/sapyexamples/output/slope_rcls")
outReclass3 = Reclassify("pop_density", "Value",
RemapRange([[10,10,1],[10,20,2],[20,25,3],
[25,50,4],[50,]]), "NODATA")
outReclass3.save("C:/sapyexamples/output/popden_rcls")
This example reclassifies the input raster based on the values in a string field.
# Name: reclassify_example02.py
# Description: Reclassifies the values in a 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 = "landuse"
reclassField = "LANDUSE"
remap = RemapValue([["Brush/transitional", 0], ["Water", 1],["Barren land", 2]])
# Check out the ArcGIS Spatial Analyst extension license
arcpy.CheckOutExtension("Spatial")
# Execute Reclassify
outReclassify = Reclassify(inRaster, reclassField, remap, "NODATA")
# Save the output
outReclassify.save("C:/sapyexamples/output/outreclass02")