docs: def get_map_matrix(inputfile):
      """ Return the matrix representation of the genetic map.
  
      :arg inputfile: the path to the input file from which to retrieve the
          genetic map.
  
      """
      matrix = read_input_file(inputfile, sep=',', noquote=True)
      output = [['Locus', 'Group', 'Position']]
      for row in matrix:
          if row[0] and not re.match(r'c\d+\.loc[\d\.]+', row[0]):
              output.append([row[0], row[1], row[2]])
      return output