Using Treemap

Treemaps display data using the relative areas of nested rectangles. See http://en.wikipedia.org/wiki/Treemapping for more information.

The TREEMAP M-file associated with this submission is one implementation of the treemap concept, but it can use your help. How would you improve its argument list (API) or its implementation? We want you to tell us.

Send your suggestions and improved code to Joe Hicklin with the subject line "treemap" (mailto:[e-mail]&subject=treemap) and we'll incorporate all the best ideas into an updated version of the code.

Contents

• By itself
• With data
• Custom colors and labels
• Another example
• Nested treemaps

By itself

You can call treemap by itself and it will run with fake data.

cla
treemap;

With data

Here's how you pass in your own data.

cla
data = rand(1,20);
treemap(data);

Custom colors and labels

You can capture the rectangles and use plotRectangles to display them with your own colors and labels.

n = 15;
data = rand(1,n);

colors = (jet(n)+1)/2;

% Add labels
labels = {};
for i = 1:n
    labels{i} = sprintf('%2.1f%%',100*data(i)/sum(data));
end

cla
rectangles = treemap(data);
plotRectangles(rectangles,labels,colors)

Another example

data = ...
{'Alaska',571951;
'Texas'	261797;
'California',155959;
'Montana',145552;
'New Mexico',121356;
'Arizona',113635;
'Nevada',109826;
'Colorado',103718;
'Oregon',95997};

colors = ones(10,3);
rectangles = treemap([data{:,2}]);
labels = data(:,1);
cla
plotRectangles(rectangles,labels,colors)
outline(rectangles)
axis([-0.01 1.01 -0.01 1.01])
title('The Ten Biggest U.S. States')

Nested treemaps

You can plot treemaps within treemaps

m = 12;
n = 20;
data = rand(m,n);

% Lay out the column totals
level1 = sum(data);

cla reset
r = treemap(level1);

% Lay out each column within that column's rectangle from the overall
% layout
for j = 1:n
    colors = (3*repmat(rand(1,3),m,1) + rand(m,3))/4;
    rNew = treemap(data(:,j),r(3,j),r(4,j));
    rNew(1,:) = rNew(1,:) + r(1,j);
    rNew(2,:) = rNew(2,:) + r(2,j);
    plotRectangles(rNew,[],colors)
end

outline(r)
axis([-0.01 1.01 -0.01 1.01])

Published with MATLAB® 7.5