code: def sub2ind(matrixSize, rowSub, colSub):
      """Convert row, col matrix subscripts to linear indices"""
      # pylint: disable=unused-variable
      m, n = matrixSize
      return rowSub * (n - 1) + colSub - 1
  
file_path: gluon-cv/gluoncv/data/kitti/kitti_utils.py
imports: from __future__ import absolute_import, division, print_function
  import os
  from collections import Counter
  import numpy
  import mxnet
label_desc: Use image node_id 3 for calling a global function with example usage: sub2ind(matrixSize, rowSub, colSub) and returns: unknown