code: def S_cluster(x, d, groupidx=[1]):
      r = np.zeros(d.shape[1])
      r[groupidx] = 1
      return aggregate_cov(x, d, r=r, weights=None)
  
file_path: statsmodels/statsmodels/sandbox/panel/sandwich_covariance_generic.py
imports: import numpy
label_desc: Use image node_id 6 for calling a global function with example usage: S_cluster(x, d, groupidx) and returns: aggregate_cov