Plotting a grid of squares in MATLAB

Question

I would like to plot a square in a 2D cartesian coordinate system with its corners at (±1,±1). I would like to further divide it to 400 smaller and equal squares each with an edge length of 0.1.

How can I do this in MATLAB?

Answer 1

You can generate the grid with the right number of vertical and horizontal lines:

%%
N = 400;
x = linspace(-1,1,sqrt(N)+1)
y = linspace(-1,1,sqrt(N)+1)

% Horizontal grid 
for k = 1:length(y)
  line([x(1) x(end)], [y(k) y(k)])
end

% Vertical grid
for k = 1:length(y)
  line([x(k) x(k)], [y(1) y(end)])
end

axis square

Answer 2

See the rectangle function. For example, try

% Draw large bounding box:
xstart = -1;
ystart = -1;

xlen = 2;
ylen = 2;

rectangle('position', [xstart, ystart, xlen, ylen])

% Draw smaller boxes
dx = 0.1;
dy = 0.1;

nx = floor(xlen/dx);
ny = floor(ylen/dy);

for i = 1:nx
    x = xstart + (i-1)*dx;
    for j = 1:ny
        y = ystart + (j-1)*dy;
        rectangle('position', [x, y, dx, dy])
    end
end

Answer 3

This looks like a problem I had to solve. What I do below is get the coordinates of all the points with meshgrid. Then I get the distance from everey point to every other point with pdist, when the distance is 1 its is a connection we want to draw. Then we plot all those lines.

%# enter your prerequisites
I=400; R=0.1; N=sqrt(I); M=sqrt(I);

%# create vertices on square grid defined by two vectors
[X Y] = meshgrid(1:N,1:M); X = X(:); Y = Y(:); 

%# create adjacencymatrix with connections between all neighboring vertices
adjacency = squareform( pdist([X Y], 'cityblock') == 1 );

%# plot adjacenymatrix on grid with scale R and origin at the center
[xx yy] = gplot(adjacency, [X Y]); 
xx = xx-round(sqrt(I)/2); %# this centers the origin
yy = yy-round(sqrt(I)/2);
plot(xx*R, yy*R)