Machine Learning Functions in Expression Language

This pages describes functions and properties that are related to the machine learning functionality in the QPR ProcessAnalyzer expression language.

MLModel

MLModel properties	Description
Type	Returns the exact type of the MLModel.

Machine Learning Functions

Function	Parameters	Description
MLModel (MLModel)	Type (string)	Create a new machine learning model for predictions. Takes type of the prediction/classification model to create as a parameter. Currently the only supported value is randomforest which uses the Accord.NET's RandomForest algorithm.
Train (MLModel)	Input data Expected outcomes Parameters	Trains given MLModel using given input data and expected outcomes. Parameters: input data: Two dimensional array where: The first dimension (rows) specifies different data points. The second dimension (columns) specifies the feature values. expected outcomes: An array of expected outcomes for each row in the input data. Must be in the same order as the rows in the input data. parameters: Additional parameters for the MLModel. Supported parameters: NumberOfTrees: the number of trees in the random forest, default value is 10. SampleRatio: the proportion of samples used to train each of the trees in the decision forest, default value is 0.632. Returns the trained MLModel object.
Transform (array)	Input data	Transforms given input data using the MLModel to generating predictions. Takes the input data as a parameter which is a two dimensional array where the first dimension (rows) specifies different data points and the second dimension (columns) specifies the feature values. Returns an array of predictions. Transformations for each row in the input data can be found at the same index of the returned array.

Examples

Example #1: Train a model using an event log and test its performance by replaying training data itself.

Def("GetOneHotColumnInformation", (
  Let("el", _),
  ToDictionary([
    "et": OrderByValue(el.EventTypes),
    "at": ToDictionary(ConcatTop(OrderByTop(el.CaseAttributes, Name).[_: Values]))
  ])
));

Def("GenerateOneHot", "cases", (
  Let("columnInformation", _),
  cases.(
    Let("cas", _),
    Flatten(
      [
        columnInformation.Get("et").(Let("et", _), If(Count(cas.EventsByType(et)) > 0, 1, 0)),
        (
          Let("atColumns", columnInformation.Get("at")),
          OrderByValue(atColumns.Keys).(
            Let("key", _),
            Let("values", atColumns.Get(key)),
            Let("caseValue", cas.Attribute(key)),
            values.(If(_ == caseValue, 1, 0))
          )
        )
      ]
    )
  )
));

Let("el", EventLogById(1));
Let("columnInformation", el.GetOneHotColumnInformation());
Let("allCases", el.Cases);
Let("allCasesOH", columnInformation.GenerateOneHot(el.Cases));
Let("trainDataOH", allCasesOH);
Let("outcomes", allCases.(Duration > TimeSpan(24)));
Let("testDataOH", allCasesOH);
Let("predictions", 
  MLModel("randomforest")
    .Train(trainDataOH, outcomes)
    .Transform(trainDataOH));
Sum(Zip(outcomes, predictions).(_[0] == _[1] != 0)) / Count(outcomes)

Example #2: Train a model using an a 75% sample of an event log and test its performance by using the rest 25% of the event log.

Def("GetOneHotColumnInformation", (
  Let("el", _),
  ToDictionary([
    "et": OrderByValue(el.EventTypes),
    "at": ToDictionary(ConcatTop(OrderByTop(el.CaseAttributes, Name).[_: Values]))
  ])
));

Def("GenerateOneHot", "cases", (
  Let("columnInformation", _),
  cases.(
    Let("cas", _),
    Flatten(
      [
        columnInformation.Get("et").(Let("et", _), If(Count(cas.EventsByType(et)) > 0, 1, 0)),
        (
          Let("atColumns", columnInformation.Get("at")),
          OrderByValue(atColumns.Keys).(
            Let("key", _),
            Let("values", atColumns.Get(key)),
            Let("caseValue", cas.Attribute(key)),
            values.(If(_ == caseValue, 1, 0))
          )
        )
      ]
    )
  )
));

Let("el", EventLogById(1));
Let("columnInformation", el.GetOneHotColumnInformation());
Let("allCases", Shuffle(el.Cases));
Let("lastTrainCaseIndex", 0.75 * CountTop(el.Cases));
Let("trainCases", allCases[NumberRange(0, lastTrainCaseIndex)]);
Let("testCases", allCases[NumberRange(lastTrainCaseIndex + 1, CountTop(el.Cases) - 1)]);
Let("trainDataOH", columnInformation.GenerateOneHot(trainCases));
Let("testDataOH", columnInformation.GenerateOneHot(testCases));
Let("trainOutcomes", trainCases.(Duration > TimeSpan(24)));
Let("testOutcomes", testCases.(Duration > TimeSpan(24)));
Let("predictions", 
  MLModel("randomforest")
    .Train(trainDataOH, trainOutcomes)
    .Transform(testDataOH));
Sum(Zip(testOutcomes, predictions).(_[0] == _[1] != 0)) / Count(testOutcomes)

Example #3: Three sets of cases: training cases, target cases (subset of training cases) and test cases (independent set of cases). Try to predict which cases in the test set will eventually end up becoming a case in target cases.

Def("GetOneHotColumnInformation", (
  Let("el", _),
  ToDictionary([
    "et": OrderByValue(el.EventTypes),
    "at": ToDictionary(ConcatTop(OrderByTop(el.CaseAttributes, Name).[_: Values]))
  ])
));

Def("GenerateOneHot", "cases", (
  Let("columnInformation", _),
  cases.(
    Let("cas", _),
    Flatten(
      [
        columnInformation.Get("et").(Let("et", _), If(Count(cas.EventsByType(et)) > 0, 1, 0)),
        (
          Let("atColumns", columnInformation.Get("at")),
          OrderByValue(atColumns.Keys).(
            Let("key", _),
            Let("values", atColumns.Get(key)),
            Let("caseValue", cas.Attribute(key)),
            values.(If(_ == caseValue, 1, 0))
          )
        )
      ]
    )
  )
));

Let("el", <event log to use>);
Let("trainCases", <cases to use for training>);
Let("targetCases", <cases representing the properties we want to try to predict (subset of traincases)>);
Let("testCases", <cases to use for testing>);
Let("targetCasesDict", ToDictionary(targetCases:true));
Let("outcomes", traincases.(Let("c", _), targetCasesDict.ContainsKey(c) ? 1 : 0));
Let("columnInformation", el.GetOneHotColumnInformation());

Let("mlModel", MLModel("randomforest"));
mlModel.Train(columnInformation.GenerateOneHot(trainCases), outcomes);
mlModel.Transform(columnInformation.GenerateOneHot(testCases));