Boolean Parameter Macro
(Custom Operators)
Synopsis
This operator can be used to define a macro which can be used by %{macro_name} in parameter values of succeeding operators of the current process. The value will be 'true' if the checkbox is checked and 'false' otherwise. This is useful for process-defined custom operators.Description
This operator can be used to define a macro which can be used in parameter values of succeeding operators of the current process. Once the macro has been defined, the value of that macro can be used as parameter values in coming operators by writing the macro name in %{macro_name} format in the parameter value where 'macro_name' is the name of the macro specified when the macro was defined. The macro name is specified by the macro parameter and the macro value is 'true' when the value parameter is selected and 'false' otherwise. The macro will be replaced in the value strings of parameters by the macro's value. This operator can also be used to re-define an existing macro.
The purpose of this operator is mainly to assist in creating process-defined custom operators. When selecting the value parameter of this operator for the custom operator, the process can make decisions based on the checkbox.
This operator sets the value of a macro irrespective of any ExampleSet. That is why this operator can also exist on its own i.e. without being connected to any other operator. If you want to create a single macro from properties of a given input ExampleSet, the Extract Macro operator is the right operator.
Macros
A macro can be considered as a value that can be used by all operators of the current process that come after the macro has been defined. Whenever using macros, make sure that the operators are in the correct sequence. It is compulsory that the macro should be defined before it can be used in parameter values. The macro is one of the advanced topics of RapidMiner, please study the attached Example Process to develop a better understanding of macros. The Example Processes of the Extract Macro operator are also useful for understanding the concepts related to the macros.
There are also some predefined macros:
- %{process_name}: will be replaced by the name of the process (without path and extension)
- %{process_file}: will be replaced by the file name of the process (with extension)
- %{process_path}: will be replaced by the complete absolute path of the process file
- Several other short macros also exist, e.g. %{a} for the number of times the current operator was applied.
Please note that other operators like many of the loop operators (e.g. Loop Values , Loop Attributes) also add specific macros.
During the runtime the defined macros can be observed in the macro viewer.
Differentiation
Set Macro
The Boolean Parameter Macro operator is like the Set Macro operator with only one difference. The Set Macro operator can be used for setting arbitrary String values while the Boolean Parameter Macro operator can only set the value to 'true' or 'false'.
Input
through (Data Table)It is not compulsory to connect any object with this port. Any object connected at this port is delivered without any modifications to the output port. This operator can have multiple inputs. When one input is connected, another through input port becomes available which is ready to accept another input (if any). The order of inputs remains the same. The object supplied at the first through input port of this operator is available at the first through output port.
Output
- through (Data Table)
Objects that were given as input are passed without changing to the output through this port. It is not compulsory to attach this port to any other port, the macro value is set even if this port is left without connections. This operator can have multiple outputs. When one output is connected, another through output port becomes available which is ready to deliver another output (if any). The order of outputs remains the same. The object delivered at the first through input port of this operator is delivered at the first through output port
Parameters
- macroThis parameter is used to specify the name of the macro. The macro can be accessed in succeeding operators of the current process by writing the macro's name in %{macro_name} format, where 'macro_name' is the name of the macro specified in this parameter. Range:
- valueThis parameter is used to specify the value of the macro. Select to change the value to 'true', otherwise the value is 'false'. When the macro is accessed in succeeding operators of the current process by writing the macro's name in %{macro_name} format, it is replaced by the value of the macro specified by this parameter. Range:
Tutorial Processes
Introduction to the Boolean Parameter Macro operator
This is a very basic process that demonstrates the use of the Boolean Parameter Macro operator. The Boolean Parameter Macro operator is used first of all. One macro is defined using the macro parameter and the value checkbox. The macro is named 'normalize' and it is given the value 'true' by selecting the checkbox. Note that this operator is not connected to any other operator; it can exist at its own. Always make sure that the macro is defined before it is used in the parameter values.
The 'Golf' data set is loaded using the Retrieve operator. The Branch operator is applied on it. Double-click on the Branch operator to see the subprocesses in it. As you can see, there are two subprocesses:
Subprocess 1 (Then): The Normalize operator is applied on the input and the resulting normalized ExampleSet is passed to the output. Subprocess 2 (Else): The input is directly connected to the output.
Only one of these subprocesses can be executed at a time. The subprocess to be executed can be controlled by the expression parameter of the Branch operator. The expression parameter is set to '%{normalize}=="true"', so it is using the 'normalize' macro defined by the Boolean Parameter Macro operator. When the process will be executed, '%{normalize}' will be replaced with the value of the 'normalize' macro i.e. '%{normalize}' will be replaced by 'true'. Thus the expression is true, thus the first subprocess will be executed. When you run the process you will see the normalized ExampleSet in the Results workspace. As the value of the expression parameter is determined by the macro created by the Boolean Parameter Macro operator, changing the checkbox will change the value of the expression parameter. To execute the second subprocess deselect the value parameter checkbox of the Boolean Parameter Macro operator and run the process again. Now you will see the unchanged 'Golf' data set in the Results Workspace because no operator was applied in the second subprocess.
This approach of using the Boolean Parameter Macro operator together with the Branch operator is very useful for creating custom operators. For creating a custom operator out of this process we would select the parameter 'value' of 'Boolean Parameter Macro' and call it 'normalize'.
