Plot in matlab, multiple plots in one figure.

Hello! I need some help with the following:

Imagine a matrix: N x 3. (an example:

if true
  % code
end
___x___ |___y___|__Z__|
 1    |   2   |  1  |
 2    |   3   |  2  |
 3    |   2   |  3  |
 4    |   2   |  4  |
 2    |   3   |  1  |
 7    |   4   |  2  |
 8    |   2   |  3  |
 8    |   2   |  4  |
 3    |   4   |  1  |

And the matrix is defined by a data list.

THE QUESTION: we want to plot the (x,y) values, for each Z value in the same coordinate system. Also we need to make it possible to see a difference between them.

I figured out the how to change the color, marking etc.

But i DO NOT know how to plot for Z = 1, Z = 2. ?

if true
  % code
end
I tried something like: 
for DATA(:,3)==1            %(the datalist called DATA)
plot(x,y,'ro')
hold on

for DATA(:,3)==2; plot(x,y,'dk') hold on etc.

but it doesn't Work! I have checked my matlab book, Google, etc. with no results! I will appreciate your help! thanks!

ib

[Image Analyst]

Are the Z all definitely integers, or can they have fractional values (in which case you'll need to bin them with hist())? And what is the "data list"? Is that what you somehow used to create the matrix of x,y,z values? Does it matter what it is, or can we just take the x,y,z matrix as a given (a starting point)?

Answer 1

[Iain]

 x_for_z1 = matrix(matrix(:,3)==1,1);
 y_for_z1 = matrix(matrix(:,3)==1,2);

plot(x_for_z1,y_for_z1,'r') hold on etc etc..

[Ibrahim]

Thanks!!!

It is B-E-A-U-T-I-F-U-L! :-D

[Image Analyst]

Note: this will not work if Z has fractional values like 2.0001 and 3.9999. See the FAQ. It will work for integers though. However you may want to do it for all Z in which case you'll want to call unique() and put lain's code into a for loop.