Help with nested for loop generating coordinates

Hello, I need to generate a list of coordinates for electrodes in an electrode array. I figured out how to do this with multiple separate for loops, but I want to find a more elegant way to do it with nested for loops

The array has 9 shanks, and each shank has 32 electrodes. I know (or can work out in my head) the xyz coordinates of the first electrode in each shank and I know the spacing between shanks and between electrodes So I created a vector with the xyz coordinates of the first electrode in the first shank

E1=[0.00470, 0.00470, 0]

Then created a for loop to iterate for the other 31 electrodes (since each electrode is 0.00005 metres further in the z axis):

for i=2:32 
    E1(i,:) = E1(1,:) + [0, 0, 0.00005*(i-1)] 
end

I then created a second matrix and for loop for the second shank (notice the first coordinate of the first row has advanced by 0.00030 because this is the distance in the x axis between shanks 1 and 2)

E2 = [0.00500, 0.00470, 0] 
for i=2:32 
    E2(i,:) = E2(1,:) + [0,0,0.00005*(i-1)]
end

I do this for all 9 shanks, changing the coordinates each time, and then concatenate the 9 arrays:

E = vertcat(E1,E2,E3,E4,E5,E6,E7,E8,E9]

I appreciate that this is a very long winded and clumsy way of doing it, so how can I create a nested for loop with one index for the shank number and a second index for the electrode number, cycling through each shank and each electrode and altering the coordinates as need to produce one continuous array of coordinates?

Answer 1

[Fabio Freschi]

The command you are looking for is meshgrid

% vectors with positions
x = 0.00470:.0003:.0071;
y = 0.00470;
z = 0:0.00005:.00155;

% grid generation (note tha y is fixed, and z and x are flipped)
[Z,Y,X] = meshgrid(z,y,x);

% electrodes
E = [X(:) Y(:) Z(:)]

[Adam Fitchett]

Thanks for your answer Is there a reason why Z and X need to be flipped in the meshgrid command?

[Adam Fitchett]

I should also mention that my y coordinates do vary, as the shanks are in a 3 by 3 grid in the xy plane. So as we pass from shank 1 to shank 9, the x and y coordinates will at points both go up and down (shank 3 is at x position 0.00530 and y position 0.00470, but shank 4 is at x position 0.00470 and y position 0.00500, and shank 8 is at x=0.00500 and y=0.00530), so I can’t simply create a grid with a linear increase in the coordinates.

[Fabio Freschi]

I flipped X and Z to have the same order you got in your example. You can also use a varying y

[Adam Fitchett]

Sure, but can I use an X and Y that vary nonlinearly i.e go up and then down and then up again?

[Fabio Freschi]

Short answer: try!