code: def bundlewarp_vector_filed(moving_aligned, deformed_bundle):
      """Calculate vector fields.
  
      Vector field computation as the difference between each streamline point
      in the deformed and linearly aligned bundles
  
      Parameters
      ----------
      moving_aligned : Streamlines
          Linearly (affinely) moved bundle
      deformed_bundle : Streamlines
          Nonlinearly (warped) bundle
  
      Returns
      -------
      offsets : List
          Vector field modules
      directions : List
          Unitary vector directions
      colors : List
      """
      points_aligned, _ = unlist_streamlines(moving_aligned)
      points_deformed, _ = unlist_streamlines(deformed_bundle)
      vector_field = points_deformed - points_aligned
  
      offsets = np.sqrt(
          np.sum((vector_field) ** 2, 1)
      )  # vector field modules
  
      # Normalize vectors to be unitary (directions)
      directions = vector_field / np.array([offsets]).T
  
      # Define colors mapping the direction vectors to RGB.
      # Absolute value generates DTI-like colors
      colors = directions
  
      return offsets, directions, colors
  
file_path: dipy/dipy/align/streamwarp.py
imports: import warnings
  import numpy
  from scipy.optimize import linear_sum_assignment
  from dipy.align.streamlinear import slr_with_qbx
  from dipy.align.cpd import DeformableRegistration
  from dipy.tracking.streamline import unlist_streamlines, Streamlines
  from dipy.stats.analysis import assignment_map
  from dipy.tracking.streamline import length
  from dipy.align.bundlemin import distance_matrix_mdf
  from dipy.viz.plotting import bundle_shape_profile
  from dipy.segment.clustering import QuickBundles
  from dipy.segment.metricspeed import AveragePointwiseEuclideanMetric
label_desc: Use image node_id 4 for calling a global function with example usage: bundlewarp_vector_filed(moving_aligned, deformed_bundle) and returns: offsets,  directions,  colors