code: def test_sparse_filtering(self):
      output = LongitudinalSamplesFilter().fit_transform(
          self.sparse_features, self.labels, self.censoring
      )
      np.testing.assert_equal(
          [out.todense() for out in output[0]], self.expected_output[0]
      )
      [
          np.testing.assert_equal(out, self.expected_output[i + 1])
          for i, out in enumerate(output[1:])
      ]
  
file_path: tick/tick/preprocessing/tests/longitudinal_samples_filter_test.py
imports: import numpy
  from scipy.sparse import csr_matrix
  import unittest
  from tick.preprocessing import LongitudinalSamplesFilter
label_desc: Use image node_id 3 for calling the Test obj's underlying member method code with example usage: obj.test_sparse_filtering() without return types