how to plot confusion matrix from confusion matrix?
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I have a confusion matrix, in numbers. I want to plot the percentage classification accuracies. I found some code from fileExchnage, but its calculating percentages wrongly. Please help to figure it out.
load confmat.mat
numlabels = size(confmat, 1); % number of labels
% calculate the percentage accuracies
confpercent = 100*confmat./repmat(sum(confmat, 1),numlabels,1);
% plotting the colors
imagesc(confpercent);
ylabel('Output Class'); xlabel('Target Class');
% set the colormap
colormap(flipud(gray));
% Create strings from the matrix values and remove spaces
textStrings = num2str(confpercent(:), '%.1f%\n%d\n');
textStrings = strtrim(cellstr(textStrings));
% Create x and y coordinates for the strings and plot them
[x,y] = meshgrid(1:numlabels);
hStrings = text(x(:),y(:),textStrings(:), ...
'HorizontalAlignment','center', 'FontSize', 38);
% Get the middle value of the color range
midValue = mean(get(gca,'CLim'));
% Choose white or black for the text color of the strings so
% they can be easily seen over the background color
textColors = repmat(confpercent(:) > midValue,1,3);
set(hStrings,{'Color'},num2cell(textColors,2));
2 Comments
Akira Agata
on 5 Dec 2019
If you have 'Deep Learning Toolbox' or 'Statistics and Machine Learning Toolbox', you can use confusionchart function to plot the chart easily.
Malathi Kunnudaiyan
on 24 Jan 2024
size(confmat, 1)
Why are we using 1 as an order here (confmat, 1)? What does it mean?
Answers (1)
Taylor
on 24 Jan 2024
load confmat.mat
% Calculate the percentage accuracy for each class
percentageAccuracies = (diag(confmat)' ./ sum(confmat, 1)) * 100;
% Plot the percentage accuracies
figure;
bar(1:11, percentageAccuracies);
xlabel('Class');
ylabel('Percentage Accuracy');
title('Classification Accuracies');
xticks(1:11); % Set x-axis ticks to represent each class
xticklabels({'Class 1', 'Class 2', 'Class 3', 'Class 4', 'Class 5', 'Class 6', 'Class 7', 'Class 8', 'Class 9', 'Class 10', 'Class 11'});
grid on; % Add grid for better readability
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