code: def ar1filter(self, xy, alpha):
      # print(alpha,)
      return (xy[1:] - alpha * xy[:-1])[self.groups_valid]
  
file_path: statsmodels/statsmodels/sandbox/regression/ar_panel.py
imports: import numpy
  from scipy import optimize
  from statsmodels.regression.linear_model import OLS
label_desc: Use image node_id 2 for calling the PanelAR1 obj's underlying member method code with example usage: obj.ar1filter(xy, alpha) and returns: unknown