Long, double, or Boolean-type variables will be enclosed in percent symbols ( % %).Layer names will be enclosed in double-quote symbols ( " ").If you select a variable from the variable list, it will be automatically added to the expression at the current cursor location. The syntax of the expression determines how variables are to be specified.The Raster Calculator tool can be used in ModelBuilder, but keep the following points in mind: Operators and tools that support deferred evaluation are included on the raster calculator tool itself either as a button or in the list of tools provided. Only operators and tools that process on a per-cell basis can take advantage of this capability. Deferred evaluation is an optimization technique where individual components of an expression are intelligently processed so as to minimize the creation of intermediate datasets on disk. The performance of an operation may be enhanced by the deferred evaluation capabilities of Map Algebra. For more information, see Complex Statement Rules. To avoid this potential problem, use appropriate parentheses in the expression so that the execution order of the operators is explicitly defined. When multiple Relational and/or Boolean operators are used consecutively in a single expression, in some cases it may fail to execute. To change the order of execution, use parentheses. Therefore, when Boolean operators are used in the same expression as Relational operators, the Boolean operators will be executed first. You can use parentheses to control the execution order.īoolean ( ~, &, ^, |) operators have a higher precedence level than Relational (, >=, =, !=) operators. For more information on operator precedence, see operator precedence table. The operator with the highest precedence value will be executed first. When multiple operators are used in an expression, they are not necessarily executed in left-to-right order. To create a raster with cells of a constant value, specify the appropriate extent and cell size environment settings and enter the numerical value into the expression. When the tool is executed, the resulting raster output will be clipped based on the specified extent. You can easily clip a raster dataset by setting the extent environment and specifying the input raster name in the expression.
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