Display sum of areas of different categories for multiple polygons in a legend

Question

Louis Helledie 2023-8-6

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2005247-display-sum-of-areas-of-different-categories-for-multiple-polygons-in-a-legend

评论： Voss 2023-8-7

polygons_brogade_foraar.csv

I have drawn multiple polygons representing different view-out categories, and have calculated the area of each individual polygon. Now i want to display the sum of the areas for each category. I have 7 categories (Other, Sky, Building, Traffic, Car, Ground and Greenery) but many of the polygons belongs to the same category (Building, Car and Greenery).

Is there a way to easily show the sum of the areas for each category in a legend on the plot? If I run the code now, it will just give me the area for each polygon instead of the area for the category, see image below.

figure;
imagesc([-pi, pi], [-1, 1], bg_img);
V = readtable('polygons_brogade_foraar.csv');
V = table2array(V);
hold on;
polygons = {
    'Other',             [-pi 1; -pi -1; pi -1; pi 1], 'white';
    'Sky',               [V(:,1) V(:,2)],              '#4DBEEE';
    'Building 1',        [V(:,3) V(:,4)],              '#A2142F';
    'Building 2',        [V(:,5) V(:,6)],              '#A2142F';
    'Traffic',           [V(:,7) V(:,8)],              '#0072BD';
    'Car 1',             [V(:,9) V(:,10)],             '#EDB120';
    'Car 2',             [V(:,11) V(:,12)],            '#EDB120';
    'Car 3',             [V(:,13) V(:,14)],            '#EDB120';
    'Ground',            [V(:,15) V(:,16)],            '#D95319';
    'Greenery 1',        [V(:,17) V(:,18)],            '#77AC30';
    'Greenery 2',        [V(:,19) V(:,20)],            '#77AC30';
    'Greenery 3',        [V(:,21) V(:,22)],            '#77AC30';
    'Greenery 4',        [V(:,23) V(:,24)],            '#77AC30';
    'Greenery 5',        [V(:,25) V(:,26)],            '#77AC30';
};
Q = polyshape(zeros(0,2));
n = size(polygons, 1);
A = zeros(1, n);
P = cell(1, n);
for k = n:-1:1
    Pk = polyshape(polygons{k, 2});
    A(k) = area(subtract(Pk, Q));
    P{k} = Pk;
    Q = union(Q, Pk);
end
for k = 1:n
    plot(P{k}, 'FaceAlpha', 1, 'FaceColor', polygons{k, 3});
end
for k = 1:n
    fprintf('Addition area polygon %d = %.2f\n', k, A(k));
end
legendStrings = cell(n, 1);
for k = 1:n
    legendStrings{k} = sprintf('%s (Area: %.2f)', polygons{k, 1}, A(k));
end
legend(legendStrings, 'Location', 'best');
axis([-pi, pi, -1, 1]);
xticks(-pi:pi/2:pi);
xticklabels({'-\pi', '-\pi/2', '0', '\pi/2', '\pi'});
title('Region of Interests (ROIs) of the 360° Video');
xlabel('Longitude');
ylabel('Latitude');
ax = gca;
set(ax, 'FontSize', 15, 'FontName', 'Bookman Old Style');

Hope I explained it well enough.

Thank you in advance,

Louis H

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Answer 1

Voss 2023-8-6

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2005247-display-sum-of-areas-of-different-categories-for-multiple-polygons-in-a-legend#answer_1284037

编辑：Voss 2023-8-6

在 MATLAB Online 中打开

polygons_brogade_foraar.csv

figure;

% imagesc([-pi, pi], [-1, 1], bg_img);

% since I don't have your variable bg_img, I set YDir 'reverse' like imagesc does

set(gca(),'YDir','reverse')

V = readtable('polygons_brogade_foraar.csv');

V = table2array(V);

hold on;

polygons = {

'Other', [-pi 1; -pi -1; pi -1; pi 1], 'white';

'Sky', V(:,[1 2]), '#4DBEEE';

'Building 1', V(:,[3 4]), '#A2142F';

'Building 2', V(:,[5 6]), '#A2142F';

'Traffic', V(:,[7 8]), '#0072BD';

'Car 1', V(:,[9 10]), '#EDB120';

'Car 2', V(:,[11 12]), '#EDB120';

'Car 3', V(:,[13 14]), '#EDB120';

'Ground', V(:,[15 16]), '#D95319';

'Greenery 1', V(:,[17 18]), '#77AC30';

'Greenery 2', V(:,[19 20]), '#77AC30';

'Greenery 3', V(:,[21 22]), '#77AC30';

'Greenery 4', V(:,[23 24]), '#77AC30';

'Greenery 5', V(:,[25 26]), '#77AC30';

};

Q = polyshape(zeros(0,2));

n = size(polygons, 1);

A = zeros(1, n);

P = cell(1, n);

for k = n:-1:1

Pk = polyshape(polygons{k, 2});

A(k) = area(subtract(Pk, Q));

P{k} = Pk;

Q = union(Q, Pk);

end