Comments on: MATLAB Basics video: Sorting matrices

By: Doug

Doug — Thu, 16 Jul 2009 14:58:08 +0000

@Mark

http://www.mathworks.com/access/helpdesk/help/techdoc/ref/sort.html

Use sort with the second output argument. That gives the absolute index, but you can use IND2SUB to get back to row and column.

-Doug

By: Mark

Mark — Wed, 15 Jul 2009 23:22:45 +0000

Hello,

I need to sort the pixel intensity values of an image in descending order, but then also be able to keep track of each intensities original coordinate in the image. I assume I will need to create an Nx3 matrix where N is the total number of pixels and the 3 column values are: 1. the pixel intensity, 2. the original col, and 3. the row coordinate.

Could you help me to get started doing this?

Thanks,
Mark

By: Doug

Doug — Wed, 22 Apr 2009 12:49:07 +0000

Renato,

What you need to do is use the transpose operator (’) to transpose the rows to columns. Then you can use sort rows and transpose right back.

Doug

By: Renato

Renato — Tue, 21 Apr 2009 19:34:34 +0000

Hi, is there any function that does the same as sortrows but for columns?

Thx for your time!

By: Doug

Doug — Tue, 23 Sep 2008 13:46:34 +0000

Sanchay,

You need to show all the relevant code to get help.

Doug

By: Sanchay Subhedar

Sanchay Subhedar — Tue, 23 Sep 2008 03:51:08 +0000

I am getting this error on using simple sort function on the same magic square as your.

??? Index exceeds matrix dimensions.

How can I “sort” this problem ;-)

By: Doug

Doug — Thu, 03 Jul 2008 13:00:22 +0000

Mayank,

Please watch the video again. You will see Sortrows at the end. This is the function you are looking for.

Doug

By: mayank

mayank — Thu, 03 Jul 2008 02:51:12 +0000

Hi,I want to sort the coordiantes.How to do this?
Eg- 1 0
3 2
21 0
4 4
2 3
5 4
so that the sorted coordinates come out to be:
1 0
21 0
3 2
2 3
4 4
5 4

By: slaesche

slaesche — Wed, 17 Oct 2007 22:42:31 +0000

Good tip! Just what I was looking for. Thanks.