Show Navigation | Hide Navigation

You are here:
Extensions > Spatial Analyst > Spatial Analyst functional reference > Math Logical (Spatial Analyst)

Is Null
Release 9.3 Last modified September 7, 2011	Print all topics in : "Math Logical (Spatial Analyst)"

Related Topics

Returns 1 if the input value is NoData and 0 for cells that are not, on a cell-by-cell basis within the Analysis window.

Learn more about how Is Null works

Illustration

Map Algebra:
OutRas = IsNull(InRas1)
Command Line:
IsNull_sa InRas1 OutRas

Usage tips

Command line and Scripting

Input values can be positive or negative.
The output value types are always integer. The values are either 1 or 0. Cells in the input that have a value are given 0 on the output. Cells that are NoData in the input are given a value of 1 on the output.
The following environment settings affect this tool:
- General: Current Workspace, Scratch Workspace, Output Coordinate system, Output Extent, Snap Raster.
- Raster Analysis: Cell size, Mask.
- Raster Storage: See the Raster Storage settings for the particular output raster format selected.

Map Algebra

Input values can be positive or negative.
The output value types are always integer. The values are either 1 or 0. Cells in the input that have a value are given 0 on the output. Cells that are NoData in the input are given a value of 1 on the output.
Learn more about how to specify the input raster dataset in the Map Algebra expression of Raster Calculator.

ArcObjects

Input values can be positive or negative.
The output value types are always integer. The values are either 1 or 0. Cells in the input that have a value are given 0 on the output. Cells that are NoData in the input are given a value of 1 on the output.
The output from the ArcObjects method is a raster object.

Command line syntax
An overview of the Command Line window
IsNull_sa <in_raster> <out_raster>

Parameter

Explanation

Data Type

<in_raster>

The input being tested to identify the cells that are NoData (null).

Composite Geodataset

<out_raster>

The output raster. Where cell values in the input are NoData, the output value will be 1. If it is any other value, the output value will be 0.

Raster Dataset

Data types for geoprocessing tool parameters

Command line example

IsNull_sa C:/data/ras_1 C:/data/final_1

Scripting syntax
About getting started with writing geoprocessing scripts
IsNull_sa (in_raster, out_raster)

Parameter

Explanation

Data Type

in_raster (Required)

The input being tested to identify the cells that are NoData (null).

Composite Geodataset

out_raster (Required)

The output raster. Where cell values in the input are NoData, the output value will be 1. If it is any other value, the output value will be 0.

Raster Dataset

Data types for geoprocessing tool parameters

Script example

# IsNull_sample.py
# Description: 
#   Returns 1 for cells in the input raster that have a value of 
#   NoData, and 0 if they do not.
# Requirements: None
# Requirements: None
# Author: ESRI
# Date: Sept 6, 2005
# Import system modules
import arcgisscripting

# Create the Geoprocessor object
gp = arcgisscripting.create()

try:
    # Set the input raster dataset
    inRaster1 = "c:/data/ras_1"

    # Set the output raster name
    outRaster = "c:/data/final_1"

    # Check out Spatial Analyst extension license
    gp.CheckOutExtension("Spatial")

    # Process: IsNull
    gp.IsNull_sa(inRaster1, outRaster)

except:
    # If an error occurred while running a tool, then print the messages.
    print gp.GetMessages()

Map Algebra syntax
IsNull(<grid>)

Parameter	Explanation
<grid>	An input integer or floating-point raster, or an expression resulting in a raster.

Map Algebra example

isnull(ingrid1)
isnull(-5.6 + ingrid1)
isnull(ingrid1 + ingrid2)
isnull(sin(ingrid1) * 4) + (focalsum(ingrid2))

ArcObjects syntax
ILogicalOp::IsNull (geoDataset As IGeoDataset) As IGeoDataset

Parameter	Explanation
geoDataset	An input Raster, RasterDataset, RasterBand, or RasterDescriptor.

ArcObjects example

' Create the RasterLogicalOp object
Dim pLogicalOp As ILogicalOp
Set pLogicalOp = New RasterMathOps

' Create the input raster object
Dim pInputDataset As IGeoDataset

' Calls function to open the input raster dataset from disk
Set pInputDataset = OpenRasterDataset("D:\SpatialData", "inputraster")

' Create the output dataset object
Dim pOutputDataset As IGeoDataset

' Calls the method
Set pOutputDataset = pLogicalOp.IsNull(pInputDataset)