Plot 10100X3 matrix as a pixel plot.

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santiago canete
santiago canete 2017-12-21
评论： Walter Roberson 2017-12-22
I have a dataset called matrix of size 10100X3. matrix(1) and matrix(2) are the x y coordinates respectively and the matrix(3) value determines the color of the pixel. This format is not working with the image() function. Any ideas on how I can make this work?
fileID1 = fopen('flipmatrix1.txt');
matrixx = fscanf(fileID1, '%f',[3,inf]);
matrixx = matrixx';
fclose(fileID1);
fileID2 = fopen('flipmatrix2.txt');
matrixy = fscanf(fileID2, '%f',[3,inf]);
matrixy = matrixy';
fclose(fileID2);
matrix = [matrixx; matrixy];
qA = matrix(:,1);
qB = matrix(:,2);
time = matrix(:,3);
image( qA, qB, time);
colorbar;
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the cyclist
the cyclist 2017-12-21

You are missing my basic point. When I said you should upload representative data, I meant that you should post a sample that should give a result with similar characteristics to what you expect. With the data and the code you shared, I get a plot that looks like this ...

This is exactly the image that I would expect from such data. So, it is not illustrating the problem you are having. We still need more information to help you.

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Walter Roberson
Walter Roberson 2017-12-21
imagesc(reshape(time, 101, 100));
After that you need to set your colormap() . Your current color values, stored in time, are scalar values in the range -4 to +30, rather than being RGB values, so to get black at the center and yellow outside you are going to need to use a colormap.
  2 个评论
Walter Roberson
Walter Roberson 2017-12-22
If this problem is solved, please Accept the answer.
I used scatter() to verify that the points were close to being on a grid, and plot() to verify that the progression was regular rather than in random order; after that it was a matter of finding the right reshape() to use. There is a possibility that your points are not exactly on the grid: if that is important then you will need to either griddata() or use surface() or patch() with texture mapping.
Getting a good colormap appears to be the major challenge.

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