code: def knn_recall(dataset_distances, run_distances, count, epsilon=1e-3):
      t = knn_threshold(dataset_distances, count, epsilon)
      actual = sum(d <= t for d in run_distances[:count])
      return actual / float(count)
  
imports: from scipy.spatial.distance import pdist
label_desc: Use image node_id 2 for calling a global function with example usage: knn_recall(dataset_distances, run_distances, count, epsilon) and returns: unknown