Lowest Position (Spatial Analyst)

Available with Spatial Analyst license.

Summary

Determines on a cell-by-cell basis the position of the raster with the minimum value in a set of rasters.

Illustration

OutRas = LowestPosition([InRas1, InRas2, InRas3])

Usage

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

• The order of the input rasters is relevant for this tool.

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

  To process a selection of bands from a multiband raster, first create a raster dataset composed of those particular bands using the Composite Bands tool; then use the result in the list in the Input rasters or constant values parameter (in_rasters_or_constants 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.

• If two or more input rasters contain the minimum value for a particular cell location, the position of the first one encountered is returned on the output raster.

• If all inputs are multidimensional raster data with the same number of variables, the tool will perform the operation for all slices with the same dimension value. The output will be a multidimensional raster in CRF format. The variables in the inputs must have at least one common dimension and one common dimensional value for this tool to process, otherwise an error will occur.

  If all of the inputs have one variable but different names, uncheck the Match Multidimensional Variable geoprocessing environment (set arcpy.env.matchMultidimensionalVariable = False in Python) before performing the operation.

  If one or more of the inputs are multidimensional rasters and the other inputs are constant, the tool will perform the operation for all slices for all variables using the constant value, and the output will be a multidimensional raster.

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

Parameters

Dialog

Label	Explanation	Data Type
Input rasters or constant values	The list of input rasters for which the position of the input with the lowest value will be determined. A number can be used as an input; however, the cell size and extent must first be set in the environment.	Raster Layer; Constant

Return Value

Label	Explanation	Data Type
Output raster	The output raster. For each cell in the output raster, the value represents the position of the raster with the lowest value.	Raster

Python

LowestPosition(in_rasters_or_constants)

Name	Explanation	Data Type
in_rasters_or_constants [in_raster_or_constant,...]	The list of input rasters for which the position of the input with the lowest value will be determined. A number can be used as an input; however, 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. For each cell in the output raster, the value represents the position of the raster with the lowest value.	Raster

Code sample

LowestPosition example 1 (Python window)

This example evaluates several input rasters and returns as an output value the position in the list of the raster with the minimum value.

import arcpy
from arcpy import env
from arcpy.sa import *
env.workspace = "C:/sapyexamples/data"
outLowestPosition = LowestPosition(["degs", "negs", "fourgrd"])
outLowestPosition.save("C:/sapyexamples/output/outlp.tif")

LowestPosition example 2 (stand-alone script)

This example evaluates several input rasters and returns as an output value the position in the list of the raster with the minimum value.

# Name: LowestPosition_Ex_02.py
# Description: Determines the position of a raster with the minimum
#              value in a set of rasters
# 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
inRaster01 = "degs"
inRaster02 = "negs"
inRaster03 = "fourgrd"

# Execute LowestPosition
outLowestPosition = LowestPosition([inRaster01, inRaster02, inRaster03])

# Save the output 
outLowestPosition.save("C:/sapyexamples/output/outlp")

Environments

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