docstr: Simulate realization in which some nodes are sometimes empty
          
docstr_tok: ["Simulate","realization","in","which","some","nodes","are","sometimes","empty"]
code: def simulate_sparse_realization(self):
      """Simulate realization in which some nodes are sometimes empty"""
      baseline = np.array([0.3, 0.001])
      adjacency = np.array([[0.5, 0.8], [0.0, 1.3]])
  
      sim = SimuHawkesExpKernels(
          adjacency=adjacency,
          decays=self.decay,
          baseline=baseline,
          verbose=False,
          seed=13487,
          end_time=500,
      )
      sim.adjust_spectral_radius(0.8)
      multi = SimuHawkesMulti(sim, n_simulations=100)
  
      adjacency = sim.adjacency
      multi.simulate()
  
      # Check that some but not all realizations are empty
      self.assertGreater(
          max(map(lambda r: len(r[1]), multi.timestamps)), 1
      )
      self.assertEqual(
          min(map(lambda r: len(r[1]), multi.timestamps)), 0
      )
  
      return baseline, adjacency, multi.timestamps
  
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 2 for calling the Test obj's underlying member method code with example usage: obj.simulate_sparse_realization() and returns: baseline,  adjacency,  multi