How to produce triangular heatmap without the baorder with imagesc?

I am trying to produce a triangular correlation plot. I can do that by putting NaNs for the upper or lower part, but then baorder showing the boundaries is also being ploted. is there way to remove it?

and produce something like this:

I attach my code and the fiugre example:

for i=1:25
        for j=1:25
if i<j
  aaa(i,j)=0;
else
  aaa(i,j)=rand(1);
end
    end
end

imagesc(aaa)
colormap(flipud(gray))

Answer 1

[Cris LaPierre]

Are you talking about the axes outline? If so, use the box function to turn it off

for i=1:25
        for j=1:25
if i<j
  aaa(i,j)=0;
else
  aaa(i,j)=rand(1);
end
    end
end

imagesc(aaa)
box off
colormap(flipud(gray))

You may also find this answer helpful: https://www.mathworks.com/matlabcentral/answers/97101-how-do-i-remove-the-border-lines-surrounding-an-axes

[Faranak]

Thanks

This is what I meant