def retrieve_positions(position_file):
  """
  This function returns a list of strings in the right format representing
  the positions that will be read out. [spatialfrequency,xi,xf,y].

  Args: 
    position_file (str): The path of the position file.

  Returns:
    positions (list,str): List representing the positions that will be read.
  """
  position_lines = open(position_file, 'r').readlines()
  positions = [line.split() for line in position_lines]
  return positions