How can I make a 2D color plot

I have an NxM matrix (B) containing values. Every value N,M corresponds to a value at that position in x,y (similarly, I also have the meshgrids for x and y). What I would like to plot is simply a contour in x,y giving in binary state whether or not the value of B is higher than a threshold. I.e. a plot where every value above threshold gives a red dot and every value below threshold gives a green dot. How do I do this?

Thanks in advance!

[jonas]

Do you want something like this?

[felix kok]

Yes please!

Answer 1

[Star Strider]

Try this:

x = rand(1, 5);                                     % Create Data
y = rand(1, 7);                                     % Create Data
[X,Y] = ndgrid(x,y);
B = rand(5, 7);                                     % Create Data
Bidx = B >= 0.5;                                    % Threshold Index
B1 = B .* Bidx;                                     % Matrix == Threshold Condition
B1(B1 == 0) = NaN;                                  % Only Plot Points Meeting Criteria
B2 = B .* ~Bidx;                                    % Matrix ~= Threshold Condition
B2(B2 == 0) = NaN;                                  % Only Plot Points Meeting Criteria

figure
scatter3(X(:), Y(:), B1(:), '.r')
hold on
scatter3(X(:), Y(:), B2(:), '.g')
hold off
view(0, 90)

[felix kok]

Thanks a lot! However, when I try your code I get the following (see image)

[Star Strider]

You did not specify the result you wanted.

Try this:

x = rand(1, 50);                                    % Create Data
y = rand(1, 70);                                    % Create Data
[X,Y] = ndgrid(x,y);
B = rand(numel(x), numel(y));                       % Create Data
Bidx = B >= 0.5;                                    % Threshold Index
B1 = B .* Bidx;                                     % Matrix == Threshold Condition

figure
hs = surf(X, Y, B1)
set(hs, 'EdgeColor','none')
view(0, 90)
colormap([1 0 0; 0 1 0])
colorbar

Experiment to get different results.