Create a 2D plot with irregular axes

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Sam Hurrell
Sam Hurrell on 2 May 2025
Commented: Sam Hurrell on 6 May 2025
I have a dataset with associated x and y coordinates, but the coordinates for both axes are not at regular intervals. Is there a way to make a map (ideally 2D but I would accept 3D) that shows these results - the values represented by colour - at their coordinates (akin to imagsc)?

Answers (2)

Star Strider
Star Strider on 2 May 2025
The plot function does not care if the data are not regularly sampled. It wil plot them appropriately regardless.
Example —
t = sort(rand(1,100));
s = sin(5*pi*t);
figure
plot(t, s, '.-')
grid
axis('padded')
sp = s;
sp(end) = NaN;
c = sp;
figure
patch(t,s,c, EdgeColor='interp',Marker='s',MarkerFaceColor='flat')
grid
axis('padded')
colormap(turbo)
I am not certain what you want.
.
  3 Comments
Star Strider
Star Strider on 5 May 2025
I am not certain what the image is, or what it represents.
A histogram2 plot could work.
Try something like this —
imshow(imread('TT3.png'))
x = randn(1000,1);
y = randn(1000,1);
figure
histogram2(x, y, 50, FaceColor='flat')
colormap(turbo)
% axis('equal')
axis('square')
view(0,90)
Make appropriate changes to get the result you want.
.
Sam Hurrell
Sam Hurrell on 6 May 2025
The attached image is a C-scan plot of data with both x and y coordiantes. The image is achieved via a wireframe plot that is made solid. The histogram plot would leave too many blank spaces that are undesirable.

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Walter Roberson
Walter Roberson on 2 May 2025
pointsize = 20;
scatter(x, y, pointsize, Dataset(:))
This will produce colored round dots at the given locations.
Producing square or rectangular dots would be more work.
  2 Comments
Walter Roberson
Walter Roberson on 3 May 2025
Ah, I guess you can specify square markers for scatter() if you need to plot squares.
Sam Hurrell
Sam Hurrell on 5 May 2025
Is there any way to merge the scatter points to create an image that looks like the attached?

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