MATLAB: Finding elements in column that meet some criteria

Question

Hello,

I have a matrix that has 3 columns and 186 rows. Values are something like this:

       Velocity         X        Y
  6.73568234861034  0  500
  6.73568234861034  2000  520
  6.73568234861034  -2000  540
  6.73568234861034  4000  560
  6.76077918572001  0  580
  6.76071354732644  6000  600

I need to transform this into matrix that will be like this

X Z Velocity

X and Z have to start from 0 and go up to maximum (8000 for x and 600 for z). This was easy. I used "sort" function, so I took care of X and Z columns.

However, now I need to figure out how to copy "Velocity" values from the first table into the second, but in a way that "Velocity" values correspond to the right value of X and Z. I guess I could use "for" loops with "if" statements, but I was wondering is there any other (easier) way; just using built-in functions?

Could you please help me with this?

Thanks, DjR

Answer 1

M=sortrows([m(:,2:3) m(:,1)],[1 2]);

Presuming m is original array w/o the header line and your "Z" is really "Y"

Or, the explicit column rearrangement can be written in a "more Matlaby" manner, and the result as

M=sortrows(circshift(m,[0 -1]),[1 2]);