How to remove contour line in filled contour plot?
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Hi all,
I am plotting a data using contourf but the there is a contour line between the start and end value color even after using the
contourf(x,y,z,'LineStyle','none','linecolor','none')
%or
contourf(x,y,z,'LineStyle','none')
%or
contourf(x,y,z,'linecolor','none')
For example in the attached figure there is a line between dark blue and dark red.
Also, I have tried different colormap but the result is same.
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/725599/image.png)
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Accepted Answer
DGM
on 31 Aug 2021
Edited: DGM
on 31 Aug 2021
Hmm. I didn't think about that. I don't know that it can be done with contourf().
% make a simple linear ramp that cycles
[xx yy] = meshgrid(1:100);
zz = xx;
zz = circshift(zz,[0 -30]);
% this is what happens with contourf()
[~,h] = contourf(xx,yy,zz,9,'linecolor','none');
colormap(jet)
colorbar
% let's try to replicate it with pcolor()
clf; pcolor(xx,yy,zz);
colormap(jet(10)) % set length to number of levels+1
colorbar
shading flat
That's about right. I think it makes the colorbar easier to read anyway.
3 Comments
DGM
on 31 Aug 2021
Edited: DGM
on 31 Aug 2021
Don't use shading interp. When you use shading interp, it will interpolate between the endpoints. It's helpful to understand that what you're looking at with pcolor() is essentially a top-down view of a surf() plot. Note how it interpolates between the maximal values and the minimal values at those boundaries. That transition is steep, but it's not perfectly vertical -- and so all those colors are visible in a narrow line.
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/725709/image.png)
Using shading flat doesn't do that:
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/725714/image.png)
and so those transition slopes don't show up:
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/725719/image.png)
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