@Test
public void testCalculatesCorrectStandardDeviations() {

    double[] expectedSigmas = new double[] {0.5, 1.47901995, 14.51723114, 0.93374247};
    final Vectorizer<Integer, Vector, Integer, Double> vectorizer = new DummyVectorizer<>(0, 1, 2, 3);
    StandardScalerPreprocessor<Integer, Vector> preprocessor = (StandardScalerPreprocessor<Integer, Vector>)standardizationTrainer.fit(
        TestUtils.testEnvBuilder(),
        datasetBuilder,
        vectorizer
    );
    assertArrayEquals(expectedSigmas, preprocessor.getSigmas(), 1e-8);
}