code: def test_quickbundles_empty_data():
      threshold = 10
      metric = dipysmetric.SumPointwiseEuclideanMetric()
      clusters = quickbundles([], metric, threshold)
      assert_equal(len(clusters), 0)
      assert_equal(len(clusters.centroids), 0)
  
      clusters = quickbundles([], metric, threshold, ordering=[])
      assert_equal(len(clusters), 0)
      assert_equal(len(clusters.centroids), 0)
  
file_path: dipy/dipy/segment/tests/test_quickbundles.py
imports: import numpy
  import itertools
  from numpy.testing import assert_array_equal, assert_equal, assert_raises
  from dipy.testing.memory import get_type_refcount
  from dipy.testing import assert_arrays_equal
  from dipy.segment.clustering import QuickBundles
  import dipy.segment.featurespeed
  import dipy.segment.metricspeed
  from dipy.segment.clustering_algorithms import quickbundles
  import dipy.tracking.streamline
  from dipy.testing.decorators import set_random_number_generator
label_desc: Use image node_id 1 for calling a global function with example usage: test_quickbundles_empty_data() without return types