code: def group_by_category(vals):
      if any(isinstance(el, list) for el in vals):
          vals = list(itertools.chain(*vals))
      val_set = list(sorted(set(vals), key=list(vals).index))
      return [val_set.index(val) for val in vals]
  
imports: import functools
  import sys
  import numpy
  import copy
  from scipy.interpolate import PchipInterpolator
  import seaborn
  import itertools
  import pandas
  from matplotlib.lines import Line2D
label_desc: Use image node_id 3 for calling a global function with example usage: group_by_category(vals) and returns: unknown