# Set Parameters (RapidMiner Studio Core)

## Synopsis

This operator applies a set of parameters to the specified operators. This operator is mostly used for applying an optimal set of parameters of one operator to another similar operator.

## Description

The Set Parameters operator takes a set of parameters as input. Operators like Optimize Parameters (Grid) or Read Parameters can be used as a source of parameter set. The Set Parameters operator takes this parameter set and assigns these parameter values to the parameters of the specified operator which can be specified through the name map parameter. This menu has two columns: 'set operator name' and 'operator name'. The 'set operator name' column is used for specifying the name of the operator (or the name of the parameter set) that generated this parameter set and the 'operator name' column specifies the name of the target operator i.e. the operator that will use this parameter set.

This operator can be very useful, e.g. in the following scenario. If one wants to find the best parameters for a certain learning scheme, one is usually also interested in the model generated with these optimal parameters. Finding the best parameter set is easily possible by operators like the Optimize Parameters (Grid) operator. But generating a model with these optimal parameters is not possible because such parameter optimization operators do not return the IOObjects produced within, but only a parameter set and a performance vector. This is, because the parameter optimization operators know nothing about models, but only about the performance vectors produced within and producing performance vectors does not necessarily require a model. To solve this problem, one can use the Set Parameters operator. Usually, a process with the Set Parameters operator contains at least two operators of the same type, typically a learner. One learner may be an inner operator of a parameter optimization scheme and may be named 'Learner', whereas a second learner of the same type named 'OptimalLearner' comes after the parameter optimization scheme and should use the optimal parameter set returned by the optimization scheme. The Set Parameters operator takes the parameter set returned by the optimization scheme as input. The name 'Learner', is specified in the 'set operator name' column and the name 'OptimalLearner' is specified in the 'operator name' column of the name map parameter. Each parameter in this list maps the name of an operator that was used during the optimization (in our case this is 'Learner') to an operator that should now use these parameters (in our case this is 'OptimalLearner'). An important thing to note here is the sequence of operators. The 'Learner', operator should be first in sequence, followed by the Set Parameters operator and finally the 'OptimalLearner' operator.

## Differentiation

### Clone Parameters

The Clone Parameters operator is a very generic form of the Set Parameters operator. It differs from the Set Parameters operator because it does not require a ParameterSet as input. It simply reads a parameter value from a source and uses it to set the parameter value of a target parameter. This operator is more generic than the Set Parameters operator and could completely replace it.

## Input

• parameter_set (Parameter Set)

This input port expects a parameter set. It is the output of the Optimize Parameters (Grid) operator in the attached Example Process. The output of other operators like the Read Parameters operator can also be used as a source of a parameter set.

## Parameters

• name_mapThe Set Parameters operator takes a parameter set and assigns these parameter values to the parameters of the specified operator which can be specified through the name map parameter. This menu has two columns i.e. 'set operator name' and 'operator name'. The 'set operator name' column is used for specifying the operator that generated this parameter set (or the name of the parameter set) and the 'operator name' column specifies the name of the target operator i.e. the operator that will use this parameter. Range: list

## Tutorial Processes

### Building a model using an optimal parameter set

The 'Polynomial' data set is loaded using the Retrieve operator. The Optimize Parameters (Grid) operator is applied on it to produce an optimal set of parameters. The X-Validation operator is applied in the subprocess of the Optimize Parameters (Grid) operator. The X-Validation operator uses an SVM (LibSVM) operator for training a model. This SVM (LibSVM) operator is named 'Learner'. After execution of the Optimize Parameters (Grid) operator, it returns a parameter set with optimal values of the C and degree parameters of the SVM (LibSVM) operator. This parameter set is provided to the Set Parameters operator. The Set Parameters operator provides these optimal parameters to the SVM (LibSVM) operator in the main process (outside the Optimize Parameter (Grid) operator). This SVM (LibSVM) operator is named 'OptimalLearner' and it comes after the Set Parameters operator in the execution sequence. Have a look at the name map parameter of the Set Parameters operator. The name 'Learner', is specified in the 'set operator name' column and the name 'OptimalLearner' is specified in the 'operator name' column of the name map parameter. Each parameter in this list maps the name of an operator that was used during the optimization (in our case this is 'Learner') to an operator that should now use these parameters (in our case this is 'OptimalLearner'). The 'OptimalLearner' uses the optimal parameters of 'Learner' and applies the model on the 'Polynomial' data set. Have a look at the parameters of the 'OptimalLearner' before the execution of the process. The degree and C parameters are set to 1 and 0.0 respectively. These values are changed to 3 and 250 after execution of the process because these are the optimal values for these parameters generated by the Optimize Parameters (Grid) operator and then these parameters were used by 'OptimalLearner'. These parameters can also be seen during the process execution (at the breakpoint after the Optimize Parameters (Grid) operator).