code: def test_combines_features_into_a_single_matrix(self):
      results = iter(
          LibSVMRankingParser(
              _TEST_DATASET.split("\n"),
              feature_names={
                  1: "bm25",
                  2: "tfidf",
                  3: "querylen",
                  4: "doclen",
                  5: "qualityscore",
              },
              combine_features=True,
          )
      )
  
      _, features = next(results)
      self.assertAllEqual(
          features["float_features"],
          [
              [1.0, 1.0, 0.0, 0.2, 0.0],
              [0.0, 0.0, 1.0, 0.1, 1.0],
              [0.0, 1.0, 0.0, 0.4, 0.0],
              [0.0, 0.0, 1.0, 0.3, 0.0],
          ],
      )
  
      _, features = next(results)
      self.assertAllEqual(
          features["float_features"],
          [
              [0.0, 0.0, 1.0, 0.2, 0.0],
              [1.0, 0.0, 1.0, 0.4, 0.0],
              [0.0, 0.0, 1.0, 0.1, 0.0],
              [0.0, 0.0, 1.0, 0.2, 0.0],
              [0.0, 0.0, 1.0, 0.1, 1.0],
              [1.0, 1.0, 0.0, 0.3, 0.0],
          ],
      )
  
      _, features = next(results)
      self.assertAllEqual(
          features["float_features"],
          [[1.0, 0.0, 0.0, 0.4, 1.0], [0.0, 1.0, 1.0, 0.5, 0.0]],
      )
  
file_path: datasets/tensorflow_datasets/ranking/libsvm_ranking_parser_test.py
imports: from tensorflow_datasets import testing
  from tensorflow_datasets.ranking.libsvm_ranking_parser import LibSVMRankingParser
  from tensorflow_datasets.ranking.libsvm_ranking_parser import ParserError
label_desc: Use image node_id 2 for calling the LibSVMRankingParserTest obj's underlying member method code with example usage: obj.test_combines_features_into_a_single_matrix() without return types