How do I create a plot like this grid in MATLAB? - matlab

Question

I have data like this
-1 -1 -1 1 0 0 1 1 -1 0 1 -1 0 1
where each element of the vector is one of a several states. In this case (which is arbitrary and obviously only an example), are -1 0 1. I'm trying to make a plot like this grid:
The closest I was able to get was with a combination of spy and various tweaks:
%% ARBITRARY example data
states = [-1 0 1];
data = [-1 -1 -1 1 0 0 1 1 -1 0 1 -1 0 1];
%% Approximate plot using sparse matrix and spy
T = size(data, 2);
num_states = size(states, 2);
g = zeros(num_states, T);
for idx = 1:T
jdx = find(data(idx) == states, 1, 'first');
g(jdx, idx) = 1;
end
g = sparse(g);
%% Tweak plot
obj = figure();
obj.Color = 'white';
spy(g, 30)
s = obj.Children(1);
s.XLim = [1 T];
s.YLim = [1 num_states];
s.XLabel.String = '';
s.XGrid = 'on';
s.YTick = 1:num_states;
s.YTickLabel = num2cell(states);
s.GridLineStyle = '-';
s.YGrid = 'on';
However, this is far from ideal, since a) it's not actually a shaded grid, and b) the ticks on the y-axis are in descending order, starting from the bottom, because this is how spy functions, among other problems. How do I make a plot like this? I'm using MATLAB 2015b on a Windows 7 64-bit machine.

Answer 1

You'll want to play around with colours and grids, but this should be sufficient to get started:
data = [-1 -1 -1 1 0 0 1 1 -1 0 1 -1 0 1];
states = flipud(unique(data)');
im = bsxfun(#eq,data,states);
image(im);
colormap([1 1 1;0 0 0]);
axis equal;
axis tight;
set(gca,'XTick',1:length(data));
grid minor
set(gca,'YTickLabel',states);
The above results in