reorder the data array for the least distance

I have a data array

a =

       1     1     1     1     1     1     1     1     1     1     1     1     1     1     1     1
       1     1     1     1     1     1     1     1     1     1     1     1     1     1     1     1
       1     1     0     0     0     0     0     1     1     0     0     0     0     0     1     1
       1     1     0     0     0     0     0     1     1     0     0     0     0     0     1     1
       1     1     0     0     0     0     0     1     1     0     0     0     0     0     1     1
       1     1     0     0     0     0     0     1     1     0     0     0     0     0     1     1
       1     1     0     0     0     0     0     1     1     0     0     0     0     0     1     1
       1     1     1     1     1     1     1     1     1     1     1     1     1     1     1     1
       1     1     1     1     1     1     1     1     1     1     1     1     1     1     1     1

Which I converted into a two column data array by picking up all the ones using

CC = bwconncomp(a) 
data = regionprops(CC, 'PixelList')

The new data is organized by rows, e.g.,

       3     1
       3     2
       3     8
       3     9
       4     1
       4     2
       4     8
       4     9
  .....

I would like to reorganize it like

       3     1
       3     2
       4     1
       4     2
  .....
       3     8
       3     9
       4     8
       4     9
  .....

so the connected points are next to each other. Any idea on how to achieve this?

Thanks!

Answer 1

[Stephen23]

You can easily use sortrows to get a very similar sequence, which keeps the connected points together, as you requested:

sortrows(data,[2,1])

Answer 2

[Feng]

Thanks, Stephen, for your help. I tried and instead of going going vertically, it is now going horizontally. The order is from RED to YELLOW as before (picture1) and after (picture2). But what I would like is from RED to GREEN as in picture1