docstr: ...Test that original coeffs are correctly retrieved when some
  realizations are empty
docstr_tok: ["...","Test","that","original","coeffs","are","correctly","retrieved","when","some","realizations","are","empty"]
code: def test_sparse(self):
      """...Test that original coeffs are correctly retrieved when some
      realizations are empty
      """
      baseline, adjacency, events = self.simulate_sparse_realization()
  
      learner = HawkesADM4(self.decay, verbose=False)
      learner.fit(events)
  
      np.testing.assert_array_almost_equal(
          learner.baseline, baseline, decimal=1
      )
      np.testing.assert_array_almost_equal(
          learner.adjacency, adjacency, decimal=1
      )
  
file_path: tick/tick/hawkes/inference/tests/hawkes_adm4_test.py
imports: import unittest
  import numpy
  from tick.hawkes import SimuHawkesExpKernels, SimuHawkesMulti
  from tick.hawkes.inference import HawkesADM4
label_desc: Use image node_id 3 for calling the Test obj's underlying member method code with example usage: obj.test_sparse() without return types