Reclassify (Spatial Analyst)

Summary

Reclassifies (or changes) the values in a raster.

Usage

• 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.

• In the tool dialog, the Classify or Unique options in the Reclassification parameter allows you to generate a remap table based on the values of the input raster. The Classify option opens a dialog and allow you to specify a method from one of the Data classification methods and number of classes. The Unique option will populate the remap table using the unique values from the input dataset.

• It is recommended to calculate statistics on a mosaic dataset before reclassifying the data.

• From the tool dialog, the remap table can be stored for future use with the Save option. You can save the remap to any relational table format. Use the Load option to reload remap tables you previously created 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.

• If the input raster has an attribute table, it will be used to create the initial reclassification table. If the input raster does not have an attribute table, you can run the Build Raster Attribute Table tool from the Data Management toolbox to build one before inputting the raster into the Reclassify tool. Otherwise, when you input the raster, a reclassification table will be created for it by first applying geoprocessing environment settings, such as Extent and Cell size, and scanning the raster.

  When the input raster is a layer from Contents, the default reclassification table will import the unique values or classified break values as specified by the layer symbology. The current geoprocessing environment settings will be ignored when importing those values. Otherwise, the reclassification must be manually entered or generated using the unique or classification options.

• Once the remap table of the reclassification has been modified, the table will not be updated if a new input raster is selected. If the reclassification is not suitable for the new raster, a new reclassification can be reinitialized by one of the following methods

  • Remove all remap records using the erase option and manually add the new values.
  • Select the unique or classification options to generate a new reclassification.

• 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 use multicore processors if available. The maximum number of cores that can be used is four.

  To use fewer cores, use the Parallel Processing Factor environment setting.

Parameters

Dialog

Label	Explanation	Data Type
Input raster	The input raster to be reclassified.	Raster Layer
Reclass field	Field denoting the values that will be reclassified.	Field
Reclassification	A remap table that defines how the values will be reclassified. Working with the table and it options are as follows: The values of the input raster can be classified as ranges of values or as individual values. The table will be displayed with Start and End values or single unique values, respectively. If the input is a layer in Contents, it will import the unique values or classified breaks of the symbology. Specify the New value that will be assigned in the output raster. Only integer values are supported. Use the Classify or Unique options to generate a remap table based on the values of the input raster. The Classify option opens a dialog and allow you to specify a method from one of the Data classification methods and number of classes. The Unique option will populate the remap table using the unique values from the input dataset. The Reverse New Values option resorts the new values list (for example, 1,2,3 becomes 3,2,1). To modify the table, new entries can be added by typing in the empty cells in the table and pressing the Enter key. This will validate the new entry and create a new, empty row for subsequent input. You can delete rows by selecting one or many rows and pressing the Delete key. Use the load and save options to save a remap for later use and apply it to other input data or for quickly repeating an analysis.	Remap
Change missing values to NoData (Optional)	Denotes whether missing values in the reclass table retain their value or get mapped to NoData. Unchecked—Signifies that if any cell location on the input raster contains a value that is not present or reclassed in a remap table, the value should remain intact and be written for that location to the output raster. This is the default. Checked—Signifies that if any cell location on the input raster contains a value that is not present or reclassed in a remap table, the value will be reclassed to NoData for that location on the output raster.	Boolean

Return Value

Label	Explanation	Data Type
Output raster	The output reclassified raster. The output will always be of integer type.	Raster

Python

Reclassify(in_raster, reclass_field, remap, {missing_values})

Name	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. RemapRange (remapTable) RemapValue (remapTable)	Remap
missing_values (Optional)	Denotes whether missing values in the reclass table retain their value or get mapped to NoData. DATA—Signifies that if any cell location on the input raster contains a value that is not present or reclassed in a remap table, the value should remain intact and be written for that location to the output raster. This is the default. NODATA—Signifies that if any cell location on the input raster contains a value that is not present or reclassed in a remap table, the value will be reclassed to NoData for that location on the output raster.	Boolean

Return Value

Name	Explanation	Data Type
out_raster	The output reclassified raster. The output will always be of integer type.	Raster

Code sample

Reclassify example 1 (Python window)

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")

Reclassify example 2 (stand-alone script)

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]])

# Execute Reclassify
outReclassify = Reclassify(inRaster, reclassField, remap, "NODATA")

# Save the output 
outReclassify.save("C:/sapyexamples/output/outreclass02")

Environments

Auto Commit, Cell Size, Cell Size Projection Method, Compression, Current Workspace, Extent, Geographic Transformations, Mask, Output CONFIG Keyword, Output Coordinate System, Parallel Processing Factor, Scratch Workspace, Snap Raster, Tile Size