Basic scorecard

Basic scorecard

Before you begin...

Download and install Titus. This article was tested with Titus 0.7.1; newer versions should work with no modification. Python >= 2.6 and < 3.0 is required.

Launch a Python prompt and import the following:

Python 2.7.6
Type "help", "copyright", "credits" or "license" for more information.
>>> import numpy
>>> 
>>> import titus.prettypfa
>>> from titus.genpy import PFAEngine

The basic form

PFA does not have a dedicated scorecard library because scorecards are both simple to evaluate using primitives and hard to generalize. This example uses extremely heterogeneous data types, including missing values (unions with null) and custom enumerations, and the model data is in the code block, rather than a cell. A more homogeneous scorecard could be relegated to a cell. It all depends on what your needs are.

pfaDocument = titus.prettypfa.jsonNode('''
metadata:
  {source: "National Stroke Foundation",
   url: "http://www.stroke.org/stroke-resources/resource-library/stroke-risk-scorecard"}
types:
  Input = record(Input,
                 blood_pressure:      double,
                 atrial_fibrillation: union(null, boolean),   // true, false, or null (unknown)
                 smoking:             union(null, boolean),
                 cholesterol:         union(null, double),
                 diabetes:            enum([yes, borderline, no], Diabetes),
                 physical_activity:   enum([none, weekly, more], PhysicalActivity),
                 weight:              enum([overweight, slightly, healthy], Weight),
                 stroke_in_family:    union(null, boolean))
input: Input
output: enum([high, caution, low], Risk)
action:
  var high = 0;
  var caution = 0;
  var low = 0;

  if (input.blood_pressure >= 140.0)
    high = high + 1
  else if (input.blood_pressure >= 120.0)
    caution = caution + 1
  else
    low = low + 1;

  ifnotnull(atrial_fibrillation: input.atrial_fibrillation) {
    if (atrial_fibrillation)
      high = high + 1
    else
      low = low + 1
  }
  else
    caution = caution + 1;

  ifnotnull(smoking: input.smoking) {
    if (smoking)
      high = high + 1
    else
      low = low + 1
  }
  else
    caution = caution + 1;

  ifnotnull(cholesterol: input.cholesterol) {
    if (cholesterol >= 240.0)
      high = high + 1
    else if (cholesterol >= 200.0)
      caution = caution + 1
    else
      low = low + 1
  }
  else
    high = high + 1;

  if (input.diabetes == Diabetes@yes)
    high = high + 1
  else if (input.diabetes == Diabetes@borderline)
    caution = caution + 1
  else
    low = low + 1;

  if (input.physical_activity == PhysicalActivity@none)
    high = high + 1
  else if (input.physical_activity == PhysicalActivity@weekly)
    caution = caution + 1
  else
    low = low + 1;

  if (input.weight == Weight@overweight)
    high = high + 1
  else if (input.weight == Weight@slightly)
    caution = caution + 1
  else
    low = low + 1;

  ifnotnull(stroke_in_family: input.stroke_in_family) {
    if (stroke_in_family)
      high = high + 1
    else
      low = low + 1
  }
  else
    caution = caution + 1;

  if (high > caution  &&  high > low)
    Risk@high
  else if (low > caution  &&  low > high)
    Risk@low
  else
    Risk@caution
''')

Test it!

Let's try every possible value in the space.

engine, = PFAEngine.fromJson(pfaDocument)

for blood_pressure in 150.0, 130.0, 110.0:
    for atrial_fibrillation in {"boolean": True}, None, {"boolean": False}:
        for smoking in {"boolean": True}, None, {"boolean": False}:
            for cholesterol in None, {"double": 210.0}, {"double": 190.0}:
                for diabetes in "yes", "borderline", "no":
                    for physical_activity in "none", "weekly", "more":
                        for weight in "overweight", "slightly", "healthy":
                            for stroke_in_family in {"boolean": True}, None, {"boolean": False}:
                                print engine.action({"blood_pressure": blood_pressure,
                                                     "atrial_fibrillation": atrial_fibrillation,
                                                     "smoking": smoking,
                                                     "cholesterol": cholesterol,
                                                     "diabetes": diabetes,
                                                     "physical_activity": physical_activity,
                                                     "weight": weight,
                                                     "stroke_in_family": stroke_in_family})