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Less Than Frequency

Available with Spatial Analyst license.

Summary

Evaluates on a cell-by-cell basis the number of times a set of rasters is less than another raster.

Illustration

Less Than Frequency illustration
OutRas = LessThanFrequency(ValRas, [InRas1, InRas2, InRas3]

Usage

  • An arbitrary number of rasters can be specified in the input rasters list.

  • When a multiband raster is specified for the Input value raster (in_value_raster in Python), only the first band will be used. To process a different band, specify the specific band to use.

  • When a multiband raster is specified as one of the Input rasters (in_rasters in Python), all the bands will be used.

    To process a selection of bands from a multiband raster, you can first create a new raster dataset composed of those particular bands with the Composite Bands tool, and use the result in the list of the Input rasters (in_rasters in Python).

  • If a cell location contains NoData on any of the input rasters, that location will be assigned NoData on the output.

  • The output raster is always of integer type.

  • See Analysis environments and Spatial Analyst for additional details on the geoprocessing environments that apply to this tool.

Syntax

LessThanFrequency (in_value_raster, in_rasters)
ParameterExplanationData Type
in_value_raster

For each cell location in the input value raster, the number of occurrences (frequency) where a raster in the input list has a lesser value is counted.

Raster Layer
in_rasters
[in_raster,...]

The list of rasters that will be compared against the value raster.

Raster Layer

Return Value

NameExplanationData Type
out_raster

The output raster.

For each cell in the output raster, the value represents the number of times that the corresponding cells in the list of rasters is less than the value raster.

Raster

Code sample

LessThanFrequency example 1 (Python window)

This example evaluates the number of times a set of input Grid rasters is less than another raster and outputs the result as an IMG raster.

import arcpy
from arcpy import env
from arcpy.sa import *
env.workspace = "C:/sapyexamples/data"
outLTF = LessThanFrequency("cost", ["degs", "negs", "fourgrd"])
outLTF.save("C:/sapyexamples/output/outltf.img")
LessThanFrequency example 2 (stand-alone script)

This example evaluates the number of times a set of input Grid rasters is less than another raster and outputs the result as an IMG raster.

# Name: LessThanFrequency_Ex_02.py
# Description: Evaluates the number of times a set of rasters is
#              less than another 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
inValueRaster = "cost"
inRaster01 = "degs"
inRaster02 = "negs"
inRaster03 = "fourgrd"

# Execute LessThanFrequency
outLTF = LessThanFrequency(inValueRaster, [inRaster01, inRaster02, inRaster03])

# Save the output 
outLTF.save("C:/sapyexamples/output/outltf")

Licensing information

  • ArcGIS Desktop Basic: Requires Spatial Analyst
  • ArcGIS Desktop Standard: Requires Spatial Analyst
  • ArcGIS Desktop Advanced: Requires Spatial Analyst

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