how to plot confusion matrix from confusion matrix?

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Hassan Ashraf
Hassan Ashraf 2019-12-5
回答： Taylor 2024-1-24
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 个评论
Akira Agata
Akira Agata 2019-12-5
If you have 'Deep Learning Toolbox' or 'Statistics and Machine Learning Toolbox', you can use confusionchart function to plot the chart easily.
Malathi Kunnudaiyan
Malathi Kunnudaiyan 2024-1-24
size(confmat, 1)
Why are we using 1 as an order here (confmat, 1)? What does it mean?

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回答（1 个）

Taylor
Taylor 2024-1-24
Ran in:
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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