MATLAB Answers

Plot Matrix as Heatmap with different cell size width

4 views (last 30 days)
Mike
Mike on 13 Aug 2021
Edited: Adam Danz on 13 Aug 2021
Hi everyone,
I have a matrix like the one below and would like to plot it as a heatmap, but the cell width of every row and colum width should be different.
For example:
x = [ 1 2 3; 4 5 6]
Cell width:
Row 1: 10 mm; Row 2: 20 mm; Row 3: 25 mm
Colum 1: 5 mm; Colum 2: 15 mm; Colum 3: 20 mm
Is this possible with a heatmap? Or is there another better way to plot this?
Greetings
Mike

Accepted Answer

Adam Danz
Adam Danz on 13 Aug 2021
Edited: Adam Danz on 13 Aug 2021
Not possible with heatmap. Here's a solution using surf.
% Inputs
data = [ 1 2 3; 4 5 6];
rowWidths = [10, 20]; %mm, one for each row of data; applied bottom to top
colWidths = [5 15 20]; %mm, one for each col of data; applied left to right
% Produce figure
fig = figure();
ax = axes(fig);
% Plot image
[xg,yg] = meshgrid([0,cumsum(colWidths)], [0,cumsum(rowWidths)]);
sh = surf(xg, yg, zeros(size(xg)), padarray(data,[1,1], 0, 'post'));
% Set colormap (this one is same as heatmap)
n = 255;
cmap = [linspace(.9,0,n)', linspace(.9447,.447,n)', linspace(.9741,.741,n)'];
colormap(ax,cmap)
cb = colorbar(ax);
axis tight
axis equal
view(2)
xlabel('mm')
ylabel('mm)')
To add text labels similar to heatmap,
% find rectangle centers
xCnt = xg(1:end-1,1:end-1) + diff(xg(1,:))/2;
yCnt = yg(1:end-1,1:end-1) + diff(yg(:,1))/2;
th = text(xCnt(:), yCnt(:), compose('%g',data(:)), ...
'HorizontalAlignment','center',...
'VerticalAlignment','middle', ...
'FontSize', 10, 'Color', 'w');
If you want the axis size to reflect the axes scales (ie, if you want the axis size to be 40x30mm), you'll need to set the axis size before plotting. It will look something like,
% Compute axis and figure size
axisSize = [sum(rowWidths), sum(colWidths)]/10; %cm, [width,height]
margins = 1; %cm margin size
figSize = (axisSize + margins*[2,2]); % cm
% Produce figure
fig = figure('Units','centimeters');
fig.Position(3:4) = figSize; % note: there is a min fig size
movegui(fig)
ax = axes('Units','centimeters',...
'Position',[margins,margins,axisSize]);

More Answers (0)

Products


Release

R2021a

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by