Calculated Attributes in QPR ProcessAnalyzer

Data to case attributes and event attributes can be originated either by

• importing them into QPR ProcessAnalyzer from a source system, csv file etc.
• calculating attribute values during model loading using an expression.

Calculated attributes have following use cases:

• Conversions: If an imported attribute data is not in a suitable format, the data can be overridden by defining a calculated attribute with the same name. The calculated attribute expression performs conversions for the data.
• Aggregations: It's possible to aggregate e.g. event level information to case level using a calculated case attribute.
• Performance improvement: If there is an expression to aggregate event level information to a case level, the aggregation can be done using a calculated case attribute to provide better performance. Then the expression can process case level only without going to the event level, which performs considerably faster, because usually there are much less cases than events.

Calculated attributes work as follows:

• Calculated attributes are treated like the imported attributes, e.g. they are available in the profiling or influence analyses. Like in the imported attributes, filtering doesn't affect the values of calculated attributes, but filtering matters when calculated attributes are aggregated, e.g. in the profiling analysis.
• Calculated attributes are calculated when the model is loaded, and thus calculated attribute values don't change after the model loading during the time the model is in the memory. If attributes need to be calculated again, the model needs to be reloaded.
• Calculated attribute values are stored into the memory as the imported attributes, meaning the model requires more memory, if there are more new calculated attributes.
• For calculated case attributes, the expression is evaluated in each case's context, and for calculated event attributes, for each event's context. It's thus possible to use the entice model in the expressions, such as variations, event types, flow and flow occurrences.
• Calculated event attributes are processed before calculated case attributes, so it's possible to use calculated event attributes in calculated case attributes expressions. Also, calculated case and event attributes are processed in the order they are defined, so it's possible to use an earlier defined calculated attribute in expressions of later attributes.
• Calculated attribute will replace an imported attribute, if there is an imported attribute with the same name. Note that it's not possible to override event timestamp, event type name or case id.
• If there is an error in the calculated attribute expression, the model loading fails, and the error needs to be corrected before the model can be used.

Calculated case and event attributes are configured to the model JSON settings are follows:

Property	Description
CaseAttributes	Array of calculated case attributes with the following properties: name: Calculated attribute name. There are no restrictions for the attribute names, but avoid names starting or ending with spaces to avoid confusion. expression: Expression to calculate the calculated attribute. The expression is calculated in the case's or event's context. Only when an expression has been defined, the attribute is a calculated attribute.
EventAttributes	Calculated event attributes are defined using the same structure as calculated case attributes.

Example 1: One calculated case attribute.

"CaseAttributes": [
  {
    "name": "Cost",
    "expression": "Cost * 1.5"
  }
}

Example 2: Two calculated event attributes:

"EventAttributes": [
  {
    "name": "Event Month",
    "expression": "Timestamp.Truncate(\"month\")"
  },
  {
    "name": "Duration to Next Event",
    "expression": "If(IsNull(_.NextInCase), null, (_.NextInCase.Timestamp-_.Timestamp))"
  }
]

Example 3: Several calculated case and event attributes:

{
"CaseAttributes": [
  {
    "name": "myBooleanAttribute1",
    "expression": "CURRENCYCODE == \"RUB\""
  },
  {
    "name": "Combined status",
    "expression": "PurchaseStatus+ \" \" + PurchaseType"
  },
  {
    "name": "Repeated Events Count",
    "expression": "Count(_.Events)-Count(Distinct(_.Events.Type))"
  },
  {
    "name": "Duration between \"Invoice Sent\" and \"Payment Received\"",
    "expression": "if(Count(_.EventsByType(\"Invoice Sent\")) == 0 || Count(_.EventsByType(\"Purchase Order Line Created\")) == 0, null, (GetAtReverse(0,_.EventsByType([\"Invoice Sent\", \"Payment Received\"])).Timestamp-GetAt(0,_.EventsByType([\"Invoice Sent\", \"Payment Received\"])).Timestamp))"
  }
],
"EventAttributes": [
  {
    "name": "Event type occurrence number",
    "expression": "Let(\"name\", _.Typename);Count(_.Recurse(_.PreviousInCase).Where(_.Typename==name))"
  }
]
}