# Less Than (Spatial Analyst)

## Summary

Performs a Relational less-than operation on two inputs on a cell-by-cell basis.

Returns 1 for cells where the first raster is less than the second raster and 0 if it is not.

## Illustration

 OutRas = LessThan(InRas1, 2)

## Usage

• Two inputs are necessary for this relational evaluation to take place.

• The order of inputs is relevant for this tool.

• In Map Algebra, the equivalent operator symbol for this tool is "<" (link).

## Syntax

LessThan (in_raster_or_constant1, in_raster_or_constant2)
 Parameter Explanation Data Type in_raster_or_constant1 The input being tested to determine if it is less than the second input. A number can be used as an input for this parameter, provided a raster is specified for the other parameter. To be able to specify a number for both inputs, the cell size and extent must first be set in the environment. Raster Layer | Constant in_raster_or_constant2 The input against which the first input is tested to be less than. A number can be used as an input for this parameter, provided a raster is specified for the other parameter. To be able to specify a number for both inputs, the cell size and extent must first be set in the environment. Raster Layer | Constant

#### Return Value

 Name Explanation Data Type out_raster The output raster.The output cell values will be either integer 0 or 1; or NoData if any input cell value is NoData. Raster

## Code Sample

LessThan example 1 (Python window)

This example performs a Relational less-than operation on two GRID rasters and outputs the result as a TIFF raster.

```import arcpy
from arcpy import env
from arcpy.sa import *
env.workspace = "C:/sapyexamples/data"
outLessThan = LessThan("degs", "negs")
outLessThan.save("C:/sapyexamples/output/outlt.tif")```
LessThan example 2 (stand-alone script)

This example performs a Relational less-than operation on two GRID rasters.

```# Name: LessThan_Ex_02.py
# Description: Performs a relational less-than operation on two inputs
#              on a cell-by-cell basis within the Analysis window
# Requirements: Spatial Analyst Extension
# Author: ESRI

# 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 = "degs"
inRaster2 = "negs"

# Check out the ArcGIS Spatial Analyst extension license
arcpy.CheckOutExtension("Spatial")

# Execute LessThan
outLessThan = LessThan(inRaster1, inRaster2)

# Save the output
outLessThan.save("C:/sapyexamples/output/outlt")```

## Licensing Information

ArcView: Requires Spatial Analyst
ArcEditor: Requires Spatial Analyst
ArcInfo: Requires Spatial Analyst

6/29/2011