Contour plot for a non rectangular object
显示 更早的评论
I have this case that I worked out in another software.
In the attached file, you can see the X,Y coordinates. The third column represents the results that I need to plot in a contour silimar to the one in the image above.
I tried several codes, but all of them plot on a rectagular area and/or not showing the same shape for the contour area. For example, the following code:
xyz = xlsread('data.xlsx');
x=xyz(2:end,1);
y=xyz(2:end,2);
z=xyz(2:end,3);
[X,Y]=meshgrid(min(x):max(x),min(y):max(y));
Z=griddata(x,y,z,X,Y);
contour(X,Y,Z)
采纳的回答
[X,Y]=meshgrid(x,y) makes a grid where all the x values are the same across the grid, and likewise for yhe y values.
You can fix it by making your own X and Y instead of using meshgrid.
Nx=41; Ny=9;
dx=1; dy=1; %adjust as desired
x=((0:Nx-1)-(Nx-1)/2)*dx; y=((0:Ny-1)-(Ny-1)/2)*dy;
[X,Y]=meshgrid(x,y); %initial approximation
Z1=X+2*Y;
subplot(211); surf(X,Y,Z1);
xlabel('X'); ylabel('Y'); axis equal; view(0,90)
%next: adjust the grid Y-values
Yadj=Y;
for i=1:Nx
if i<=5||i>=37
ymult=1;
elseif i>=32
ymult=(i-25)/12;
elseif i<=10
ymult=(17-i)/12;
else
ymult=0.5;
end
Yadj(:,i)=ymult*Y(:,i);
end
subplot(212); surf(X,Yadj,Z1);
xlabel('X'); ylabel('Yadj'); axis equal; view(0,90)
It works. The code to adjust the y-values is not very elegant, but it demonstrates the possibilities for creating a non-retangular grid.
4 个评论
@Ghazwan, you can use this approach to make a surface plot with polar coordinates:
Nh=36; Nr=9; %grid dimensions: angle, radius
R=2; %max radius, adjust as desired
dr=R/(Nr-1); %delta r
theta=(0:Nh)*2*pi/Nh; %vector of angles
r=0:dr:R; %vector of radii
[Radius,Theta]=meshgrid(r,theta); %grid arrays
Z=cos(Theta).*sin(pi*Radius/R)/2; %compute Z=Z(r,theta)
X=Radius.*cos(Theta); %X cooridnates for plotting
Y=Radius.*sin(Theta); %Y coordinates for plotting
surf(X,Y,Z); %plot the surface
xlabel('X'); ylabel('Y'); zlabel('Z'); axis equal;
It is a start for polar grid plot.
You can also make a grid on an annulus, by a slight modificaiton of the code above:
Nh=72; Nr=9; %grid dimensions: angle, radius
Rin=1; Rout=2; %max radius, adjust as desired
dr=(Rout-Rin)/(Nr-1); %delta r
theta=(0:Nh)*2*pi/Nh; %vector of angles
r=Rin:dr:Rout; %vector of radii
[Radius,Theta]=meshgrid(r,theta); %grid arrays
Z=cos(2*Theta).*sin(pi*(Radius-Rin)/(Rout-Rin)); %compute Z=Z(r,theta)
X=Radius.*cos(Theta); %X cooridnates for plotting
Y=Radius.*sin(Theta); %Y coordinates for plotting
surf(X,Y,Z,'EdgeColor','none'); %plot surface
xlabel('X'); ylabel('Y'); zlabel('Z'); axis equal; view(0,90)
Try it.
Ghazwan
2022-10-6
William Rose
2022-10-6
@Ghazwan, you are welcome. Your plan sounds good.
更多回答（0 个）
类别
在 帮助中心 和 File Exchange 中查找有关 Contour Plots 的更多信息
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!
Translated by 
