R Script Nodes in Policy Designer

The Properties window for an R Script node contains the items that are described in the following table.

Item	Description	Notes
Path	Specifies the path to the R script that will run when the policy is executed.	You can type the path manually, or you can browse to it by selecting .
Additional sections corresponding to the inputs expected by the R script.	Specifies the values that will be used in the R script to calculate a result.	The number of sections displayed in the Properties window is determined by the number of inputs configured in the specified R script. In each section, you can select the icon to specify the output of a predecessor node. The value that you specify should correspond to the type of input expected by the R Script (i.e., a Vector of Values, a Matrix of Values, Data Frame, or a single value that is Numeric, Character, Boolean, or Time & Date).

You should account for the following behaviors when working with R scripts in policies:

• The policy execution engine sends date inputs to the R script in UTC. If your R script performs any calculations based on dates, the date output must also be in UTC and use the standard date format yyyy-MM-dd hh:mm:ss.fff.
• For Vector, Matrix and Data Frame inputs, the collections that you specify cannot contain any null values.

• For Data Frame inputs:

  • The entire collection you specify is passed to the R script.
  • The supported data types for each column are Time & Date, Numeric, Character, and Boolean.
  • Reading values in readings collections specified directly from an input node such as the OPC Tag, Measurement Location, or Health Indicator node are untyped and therefore sent to the R script as string values.

The following example illustrates how you can use an R Script node to evaluate certain values in other nodes and return a particular value. Consider the following nodes and connections.

As shown in the following image, you can use the Properties window for the R Script node to select a particular R script that was created using the R script editor. The R script in this example requires three input values: LinerBaseDF, LiningConditionAdjustment, and OnlineMonitoringAdjustment. These input values correspond to variables in the specified R script.

You can see that output values from the predecessor Input nodes have been specified to supply the values required by the R script. When this policy is executed, these values will be used to calculate the result of the R script. The Return Value node then returns the value calculated by the R Script node.

The following example illustrates how you can use a policy to execute an R script that calculates statistical information regarding readings related to a Measurement Location, and then send that information via email message to a designated recipient.

Consider the following R script and corresponding parameters.

This R script calculates the average reading value, count of readings, standard deviation, and most recent reading date of input values provided as a Data Frame.

The following policy is used to provide the input to the R script and to use the results of the R script in subsequent operations.

This policy first filters Measurement Location readings to only those readings recorded within the last 30 days. Then, the filtered readings are sent as a Data Frame input to the R script.

The following image shows the Properties window for the R Script node.

Next, the calculated results returned by the R script are used in a Text node to construct a message that will ultimately be sent via email to a responsible user.

The following image shows the Properties window for the Text node.

The following image shows the full text pattern specified in the Text node.