code: def index_pix_in_pixels(pix,pixels,sort=False,outside=-1):
      if sort: pixels = np.sort(pixels)
      index = np.searchsorted(pixels,pix)
      if np.isscalar(index):
          if not np.in1d(pix,pixels).any(): index = outside
      else:
          index[~np.in1d(pix,pixels)] = outside
      return index