How to plot 2D colormap or heatmap?

Question

ishita agrawal 2017-6-28

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https://ww2.mathworks.cn/matlabcentral/answers/346669-how-to-plot-2d-colormap-or-heatmap

回答： Image Analyst 2018-8-29

I have 2 matrices, x and y each containing 100-200 datapoints. I want to plot heatmap (or 2D colormap) to show density. For example, x= 1:100; for i=1:100 y=rand(0.01:1); end

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Answer 1

Image Analyst 2017-6-28

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https://ww2.mathworks.cn/matlabcentral/answers/346669-how-to-plot-2d-colormap-or-heatmap#answer_272281

Try scatteredInterpolant() to generate a 2-D image from randomly scattered points, then use imshow() to display it, and colormap() to apply a colormap, and colorbar() to show a bar alongside the image.

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Anjali Gerg 2018-8-29

while applying imshow() function to the object generated after scatteredInterpolation, it says the input number must be a number or logical. Can you suggest how we can apply imshow() after using scatterInterpolation?

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Answer 2

Image Analyst 2018-8-29

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https://ww2.mathworks.cn/matlabcentral/answers/346669-how-to-plot-2d-colormap-or-heatmap#answer_334590

在 MATLAB Online 中打开

Here is a snippet from my program:

% Make the scattered interpolant.
F = scatteredInterpolant(xi, yi, dataValues)
  
% Get a grid of points at everypixel location in the RGB image.
[xGrid, yGrid] = meshgrid(1:columns, 1:rows);
xq = xGrid(:);
yq = yGrid(:);
  
% Evaluate the interpolant at query locations (xq,yq).
vq = F(xq, yq);
fittedImage = reshape(vq, rows, columns);
imshow(fittedImage, []);