How to make a contourf plot follow a line?
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Good morning! I plotted a contourf plot in a figure, until then evrything is working, but now, I awant to make that contour follow a line. I have been trying to use a for loop but I cannot make it work. Any idea on what I could try to achieve my goal?
Here is my foor loop:
for i = 1:200
c = contourf(X, Y, -) %% different variables from my code to make it easier
xticks([])
yticks([])
cmap = colormap("summer");
xline(0, "black", "LineWidth", 2)
view([180 90]); % changes the view so that the pattern is facing down
pause(2)
drawnow
end
Thank you
2 Comments
Mathieu NOE
on 23 Jun 2023
Edited: Mathieu NOE
on 23 Jun 2023
hello
can you share your data ? and a picture / sketch of what you want to achieve
Accepted Answer
Mathieu NOE
on 23 Jun 2023
hello again
here a small demo code based on a first given elipse (bottom left on the picture)
you can use a spacing between them if needed (xr_spacing)
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1417988/image.png)
the intersections function is attached
% dummy ellipse
n = 100;
alpha = pi/n+(0:n)/n*2*pi;
a = 1;
b = 3;
x0 = 2.5;
y0 = 3;
x = x0 + a*cos(alpha);
y = y0 + b*sin(alpha);
% create the reference line
xref = (0:0.1:10);
yref = y0*ones(size(xref));
figure(1);
plot(x,y,'*-b',xref,yref,'r--')
xlim([0 8])
ylim([0 8])
axis square
% for fun let's apply a rotation angle to this
% rotation around the origin(0,0)
% Create rotation matrix
theta = 45; % to rotate 25 degrees counterclockwise
R = [cosd(theta) -sind(theta); sind(theta) cosd(theta)];
% Rotate your point(s)
for k =1:numel(x)
rotpoint = R*([x(k) ;y(k)]);
xr(k) = rotpoint(1);
yr(k) = rotpoint(2);
end
for k =1:numel(xref)
rotpoint = R*([xref(k) ;yref(k)]);
xrefr(k) = rotpoint(1);
yrefr(k) = rotpoint(2);
end
%
figure(2);
plot(xr,yr,'*-b',xrefr,yrefr,'r--')
xlim([-4 8])
ylim([0 12])
axis square
hold on
% now create replicates of the rotated elipse along the reference line
% intersections makes finding the intersection points very easy.
[xout,yout] = intersections(xr,yr,xrefr,yrefr,1);
dx = diff(xout);
dy = diff(yout);
% do n duplicates
xr_spacing = 0.25; % along the reference line (rotated)
xy_spacing = R*([xr_spacing ;0]); % gives the true x and y spacing in the absolute referential
for n = 1:3
newx = xr + n*(dx+xy_spacing(1));
newy = yr + n*(dy+xy_spacing(2));
plot(newx,newy);
end
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