Test directional expectation

test_directional_expectation.py

def test_dt_directional_expectation(dummy_titanic_dt, dummy_passengers):
    model = dummy_titanic_dt
    _, p2 = dummy_passengers

    # Get original survival probability of passenger 2
    test_df = pd.DataFrame.from_dict([p2], orient='columns')
    X, y = get_feats_and_labels(prep_df(test_df))
    p2_prob = model.predict(X)[0]  # 1.0

    # Change gender from female to male
    p2_male = p2.copy()
    p2_male['Name'] = ' Mr. John'
    p2_male['Sex'] = 'male'
    test_df = pd.DataFrame.from_dict([p2_male], orient='columns')
    X, y = get_feats_and_labels(prep_df(test_df))
    p2_male_prob = model.predict(X)[0]  # 0.56

    # Change class from 1 to 3
    p2_class = p2.copy()
    p2_class['Pclass'] = 3
    test_df = pd.DataFrame.from_dict([p2_class], orient='columns')
    X, y = get_feats_and_labels(prep_df(test_df))
    p2_class_prob = model.predict(X)[0]  # 0.0

    # Lower fare from 71.2833 to 5
    p2_fare = p2.copy()
    p2_fare['Fare'] = 5
    test_df = pd.DataFrame.from_dict([p2_fare], orient='columns')
    X, y = get_feats_and_labels(prep_df(test_df))
    p2_fare_prob = model.predict(X)[0]  # 0.85

    assert p2_prob > p2_male_prob, 'Changing gender from female to male should decrease survival probability.'
    assert p2_prob > p2_class_prob, 'Changing class from 1 to 3 should decrease survival probability.'
    assert p2_prob > p2_fare_prob, 'Changing fare from 72 to 5 should decrease survival probability.'