Add neighbor cutoff r_ij <= 3*r_soc to intrusion computation

Per Cordes2024 Eq. 1, the neighbor set N_i is restricted to agents
within r_ij <= 3*r_soc. Without this filter, distant agents contribute
small but accumulating spurious values to the intrusion number.

Author: chraibi

pedpy/methods/foo_calculator.py

@@ -51,6 +51,7 @@ def compute_intrusion(
         pandas.DataFrame: _description_
     """
     intrusion = _compute_individual_distances(traj_data=traj_data)
+    intrusion = intrusion[intrusion.distance <= 3 * r_soc]
     intrusion[INTRUSION_COL] = (
         (r_soc - l_min) / (intrusion.distance - l_min)
     ) ** 2