Calculate Value (ModelBuilder)

Summary

Returns a value based on a specified Python expression.

Learn how Calculate Value works in ModelBuilder

Usage

• This tool is only available from ModelBuilder for use in models. The tool is not available from the Geoprocessing pane or from Python.

• The Expression parameter only supports Python expressions. Other scripting languages are not supported.

• Use the Expression parameter for short one line expressions. Use the Code Block parameter for more complicated expressions, such as multiline calculations or logical operations (if, then). The Code Block parameter cannot be used on its own; it must be used in conjunction with the Expression parameter.

  See examples of using the Expression parameter.

• Variables created in ModelBuilder can be used by this tool, but they cannot be used directly in the Expression parameter. To use a variable in the expression, enclose the variable name in percent signs (%) or double-click the variable name in the Variables list to add it to the Expression parameter.

• To use a Python function in an expression, double-click a function in the Functions list to add it to the Expression parameter.

  

• You cannot access model variables in the Code Block parameter. These variables must be passed to the code block from the expression. To do this, create a function definition in the Code Block parameter and reference the definition in the Expression parameter.

  See examples of using the Code Block parameter.

• The Data Type parameter is used in ModelBuilder to help chain the output of this tool with other tools. For example, if you use this tool to calculate a distance for use as input to the Buffer Distance parameter of the Buffer tool, specify Linear Unit for the Data Type parameter value.

  See examples of using the Data Type parameter.

• In Python, proper indentation is part of the syntax. The indentation level (two spaces or four spaces) does not matter as long as it is consistent throughout the code block.

Note:

When writing equivalent Python scripts, use standard Python statements instead of using this tool.

Parameters

Dialog

Label	Explanation	Data Type
Expression	The Python expression that will be evaluated. Use the Expression parameter for short one line expressions. Use the Code Block parameter for more complicated expressions, such as multiline calculations or logical operations (if, then). The Code Block parameter cannot be used on its own; it must be used in conjunction with the Expression parameter.	SQL Expression
Code Block (Optional)	A Python code block. The code in the code block must be referenced in the Expression parameter.	String
Data type (Optional)	Specifies the data type of the return value of the Python expression. This parameter helps chain Calculate Value with other tools. 3D Object Feature Layer—3D Object Feature Layer Address Locator—Address Locator Analysis Cell Size—Analysis Cell Size Annotation Layer—Annotation Layer Any Value—Any Value ArcMap Document—ArcMap Document Areal Unit—Areal Unit BIM File Workspace—BIM File Workspace Boolean—Boolean Building Discipline Layer—Building Discipline Layer Building Scene Discipline Layer—Building Scene Discipline Layer Building Layer—Building Layer Building Scene Layer—Building Scene Layer CAD Drawing Dataset—CAD Drawing Dataset Calculator Expression—Calculator Expression Catalog Layer—Catalog Layer Catalog Root—Catalog Root Cell Size—Cell Size Cell Size XY—Cell Size XY Composite Layer—Composite Layer Compression—Compression Coordinate System—Coordinate System Coordinate Systems Folder—Coordinate Systems Folder Coverage—Coverage Coverage Feature Class—Coverage Feature Class Data Element—Data Element Data File—Data File Database Connections—Database Connections Dataset—Dataset Date—Date dBASE Table—dBASE Table Decimate—Decimate Diagram Layer—Diagram Layer Dimension Layer—Dimension Layer Disk Connection—Disk Connection Double—Double Elevation Surface Layer—Elevation Surface Layer Encrypted String—Encrypted String Envelope—Envelope Evaluation Scale—Evaluation Scale Extent—Extent Extract Values—Extract Values Feature Class—Feature Class Feature Dataset—Feature Dataset Feature Layer—Feature Layer Feature Set—Feature Set Field—Field Field Info—Field Info Field Mappings—Field Mappings File—File Folder—Folder Formulated Raster—Formulated Raster Fuzzy Function—Fuzzy Function GeoDataServer—GeoDataServer Geodataset—Geodataset Geometric Network—Geometric Network Geostatistical Layer—Geostatistical Layer Geostatistical Search Neighborhood—Geostatistical Search Neighborhood Geostatistical Value Table—Geostatistical Value Table GlobeServer—GlobeServer GPServer—GPServer Graph—Graph Graph Data Table—Graph Data Table Graphics Layer—Graphics Layer Group Layer—Group Layer Horizontal Factor—Horizontal Factor Image Service—Image Service Index—Index INFO Expression—INFO Expression INFO Item—INFO Item INFO Table—INFO Table Internet Tiled Layer—Internet Tiled Layer KML Layer—KML Layer LAS Dataset—LAS Dataset LAS Dataset Layer—LAS Dataset Layer Layer—Layer Layer File—Layer File Layout—Layout Line—Line Linear Unit—Linear Unit Long—Long M Domain—M Domain Map—Map Map Server—Map Server Map Server Layer—Map Server Layer Mosaic Dataset—Mosaic Dataset Mosaic Layer—Mosaic Layer Neighborhood—Neighborhood Network Analyst Class FieldMap—Network Analyst Class FieldMap Network Analyst Hierarchy Settings—Network Analyst Hierarchy Settings Network Analyst Layer—Network Analyst Layer Network Data Source—Network Data Source Network Dataset—Network Dataset Network Dataset Layer—Network Dataset Layer Network Travel Mode—Network Travel Mode Oriented Imagery Layer—Oriented Imagery Layer Parcel Fabric—Parcel Fabric Parcel Fabric for ArcMap—Parcel Fabric for ArcMap Parcel Fabric Layer for ArcMap—Parcel Fabric Layer for ArcMap Parcel Layer—Parcel Layer Point—Point Polygon—Polygon Projection File—Projection File Pyramid—Pyramid Radius—Radius Random Number Generator—Random Number Generator Raster Band—Raster Band Raster Calculator Expression—Raster Calculator Expression Raster Catalog—Raster Catalog Raster Catalog Layer—Raster Catalog Layer Raster Data Layer—Raster Data Layer Raster Dataset—Raster Dataset Raster Layer—Raster Layer Raster Statistics—Raster Statistics Raster Type—Raster Type Record Set—Record Set Relationship Class—Relationship Class Remap—Remap Report—Report Route Measure Event Properties—Route Measure Event Properties Scene Layer—Scene Layer Semivariogram—Semivariogram ServerConnection—ServerConnection Shapefile—Shapefile Spatial Reference—Spatial Reference SQL Expression—SQL Expression String—String String Hidden—String Hidden Table—Table Table View—Table View Terrain Layer—Terrain Layer Text File—Text File Tile Size—Tile Size Time Configuration—Time Configuration Time Unit—Time Unit TIN—TIN TIN Layer—TIN Layer Tool—Tool Toolbox—Toolbox Topo Features—Topo Features Topology—Topology Topology Layer—Topology Layer Trace Network—Trace Network Trace Network Layer—Trace Network Layer Trajectory Layer—Trajectory Layer Transformation Function—Transformation Function Utility Network—Utility Network Utility Network Layer—Utility Network Layer Variant—Variant Vector Tile Layer—Vector Tile Layer Vertical Factor—Vertical Factor Voxel Layer—Voxel Layer VPF Coverage—VPF Coverage VPF Table—VPF Table WCS Coverage—WCS Coverage Weighted Overlay Table—Weighted Overlay Table Weighted Sum—Weighted Sum WMS Map—WMS Map WMTS Layer—WMTS Layer Workspace—Workspace XY Domain—XY Domain Z Domain—Z Domain	String

Derived Output

Label	Explanation	Data Type
Value	The calculated value.	Data Element; Layer; Table View

Environments

This tool does not use any geoprocessing environments.

Licensing information

• Basic: Yes
• Standard: Yes
• Advanced: Yes