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Need to plot speed heatmap

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Laxmi Bhatta
Laxmi Bhatta on 14 Mar 2023
Commented: Laxmi Bhatta on 14 Mar 2023
I have an excel sheet having data of time, distance(postmile) and speed in three columns
I have to plot 2d high resolution heatmap of speed as follows; time in x-axis, distance(postmile) in y axis and speed in z axis with color. Can anyone help me to provide matlab code for this

Answers (1)

Anurag Ojha
Anurag Ojha on 14 Mar 2023
Hi, Laxmi
To draw a heatmap for 3 variables you can simply turn your data into an image, for example, a 1000x1000 image. Then display the image using imshow or “image” and then use “colormap” and “colorbar.
%Taken 3 variables in your case time,displacement and speed
x = 1:100;
y = 2:102;
z = 50:150;
% Doing this so that any unassigned values
% (like you don't have every single possible x and y value in your data) will be
% set to the mean value of what data you do have.
minx = min(x);
maxx = max(x);
miny = min(y);
maxy = max(y);
meanValue = mean(z);
heatMapImage = meanValue * ones(1000, 1000);
% Here creating the heatmap and storing it in heatMapImage array
for k = 1 : length(x)
column = round( (x(k) - minx) * 100 / (maxx-minx) ) + 1;
row = round( (y(k) - miny) * 100 / (maxy-miny) ) + 1;
heatMapImage(row, column) = z(k);
end
%Convert the array to image using imshow and adding colorbar
imshow(heatMapImage, []);
colormap('hot');
colorbar;
To further explore you can refer to below links:
Hope it helps!
  1 Comment
Laxmi Bhatta
Laxmi Bhatta on 14 Mar 2023
Hi there
I have attached table, I am new to MATLAB, if you could make code for plotting one heatmap having time in x (column3) axis, postmile in y axis (column 2) and speed (column 4) in z axis would be appreciated.
Thanks

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