# Heat Map Representation of error data

조회 수: 10 (최근 30일)
RAJEEV . 2023년 9월 13일
답변: Mathieu NOE . 2023년 9월 14일
I have an error matrix consisting of positive and negative difference between the theoritical and practical values. I want to select the cell containing lowest positive number using heat map and ignore the negative numbers. How to do that ?
P.S. : This is a part of bigger program where difference in RMSE values of training and validation datasets represents the above error matrix.

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### 답변 (1개)

Mathieu NOE 2023년 9월 14일
hello
I could suggest these two solutions
either based on the regular heatmap function and creating a specific colormap
the limited range that includes your min positive value is coded in red (up to you to change to another color) or second solution is based on a Fex submission (as far as I can remember, tx to his creator !) err_pos = err;
err_pos(err_pos<0) = NaN;
[min_val,id]= min(err_pos,[],'all','linear'); % min positive value and linear indice
[r,c] = ind2sub(size(err),id); % convert linear indice to row / col indices
%% solution #1
figure(1)
max_val = max(abs(err),[],'all');
% this colormap will span values from -max_val to +max_val
n = 2*ceil(max_val/min_val)+1; % odd number
cmap = gray(n);
% create a "red" zone between 0 and a value slightly above the min error
rz = (n-1)/2; % row index correponding to zero
cmap((rz:rz+2),1) = 1; %
cmap((rz:rz+2),2:3) = 0; %
% create the heatmap
h = heatmap(err,'GridVisible',false);
% apply the colormap
colormap(cmap)
% % apply the color limits (full range of the data)
caxis([-max_val max_val])
%% solution #2
figure(2)
matvisual(err, 'annotation')
hold on
plot(c,r,'ro','markersize',60);
hold off
% +------------------------------------------------------+
% | Matrix Visualization with MATLAB Implementation |
% | |
% | Author: Ph.D. Eng. Hristo Zhivomirov 12/02/18 |
% +------------------------------------------------------+
%
% function: matvisual(A, varargin)
%
% Input:
% A - m-by-n-by-p matrix to be visualized
% varargin - type 'annotation' in the place of varargin if one wants to
% annotate the matrix plot (x-label, y-label, etc.)
% example :
% %% generate a test matrix
% % A = eye(10);
% % A = magic(30);
% % A = ones(10);
% % A = zeros(10);
% % A = NaN(10);
% % A = Inf(10);
% % A = rand(20, 10, 3);
% A = round(10*rand(50, 50));
% % A = round(10*rand(10, 5, 5));
% % A = abs(fft(1:10));
% % A = complex(rand(5,5), rand(5,5));
% % A = char(1300*ones(10));
% % A = zeros(0, 20);
%
% %% visualize the matrix
% matvisual(A, 'annotation')
function matvisual(A, varargin)
% input validation
validateattributes(A, {'single', 'double', 'logical'}, ...
{'3d', 'nonempty', 'real'}, ...
'', 'A', 1)
% determine the matrix size
[M, N, P] = size(A);
% loop through the matrix pages
for p = 1:P
% get prepared for page-by-page visualization
if P > 1, subplot(1, P, p), end
% visualize the matrix
himg = imagesc(A(:, :, p));
grid on
% values labeling
for m = 1:M
for n = 1:N
text(n, m, num2str(A(m, n, p), 3), ...
'FontName', 'Times New Roman', ...
'FontSize', round(6 + 50./sqrt(M.*N)), ...
'HorizontalAlignment', 'center', ...
'Rotation', 45)
end
end
% annotation
if strcmp(varargin, 'annotation')
% x-label, y-label, x-ticks, y-ticks, title
set(gca, 'FontName', 'Times New Roman', 'FontSize', 12)
xlabel('Column number')
ylabel('Row number')
if P > 1, title(['Matrix page ' num2str(p)]), end
if M <= 50, set(gca, 'YTick', 1:M), end
if N <= 50, set(gca, 'XTick', 1:N), end
end
% set the datatip UpdateFcn
cursorMode = datacursormode(gcf);
set(cursorMode, 'UpdateFcn', {@datatiptxt, himg})
end
end
function text_to_display = datatiptxt(~, hDatatip, himg)
% determine the current datatip position
pos = get(hDatatip, 'Position');
% form the datatip label
text_to_display = {['Row: ' num2str(pos(2))], ...
['Column: ' num2str(pos(1))], ...
['Value: ' num2str(himg.CData(pos(2), pos(1)))]};
end

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