Plotting discretized field in 2D

I have x,y Cartesian Coordinates and a value next to them that I would like to plot in color in the corresponding x,y.

xy = linspace(0,20,11);
x_y_value = [(combvec(xy,xy) )' rand(121,1)];

Here I would like to plot 2x2 squares at x,y (two first columns of x_y_value matrix) colored according to the value (third column of x_y_value matrix).

I am looking something like the attached image.

Thank you

Answer 1

[Anton Semechko]

Here is an example:

x_lim=[0 20];
x=linspace(x_lim(1),x_lim(2),11);
[X,Y]=meshgrid(x);
F=randn(size(X)).*X-randn(size(X)).*Y;

figure('color','w')
imagesc(x_lim,x_lim,F)
axis equal
set(gca,'XLim',x_lim+[-1 01],'YLim',x_lim+[-1 1])

[Spyros Polychronopoulos]

Thank you Anton Semechko,

Is there maybe a way to just plot the square points at x,y coordinates without having to create an 11x11 matrix (F) but rather having the values of each point in a 1x121 matrix?

[Anton Semechko]

Yep, here is one approach:

xy = linspace(0,20,11);
x_y_value = [(combvec(xy,xy) )' rand(121,1)];
figure('color','w')
sz=1000; % size of the squares
h=scatter(x_y_value(:,1),x_y_value(:,2),sz,x_y_value(:,3),'filled','s');
axis equal

[Spyros Polychronopoulos]

Thank you very much Anton, it worked nicely. The only issue is that I set the squares to be sz=1000 and then I have gaps between them or when I zoom in/out they are not 1by1 anymore. Please check the attached plots.

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[Anton Semechko]

Ok, here is yet another approach:

xy = linspace(0,20,11);
x_y_value = [(combvec(xy,xy) )' rand(121,1)];
N=size(x_y_value,1);

dx=xy(2)-xy(1);
C=(dx/2)*[-1 -1; 1 -1; 1 1; -1 1];

figure('color','w')
for i=1:N
    Ci=bsxfun(@plus,C,x_y_value(i,1:2));
    h=fill(Ci(:,1),Ci(:,2),x_y_value(i,3));
    set(h,'EdgeColor','k')
    hold on
end
axis equal

XLim=[min(x_y_value(:,1)) max(x_y_value(:,1))]+dx*[-1 1];
YLim=[min(x_y_value(:,2)) max(x_y_value(:,2))]+dx*[-1 1];
set(gca,'XLim',XLim,'YLim',YLim)

[Spyros Polychronopoulos]

This is exactly what I was looking for! I have never came across bsxfun. Thank you again Anton!

[Anton Semechko]

You are welcome!