How do I plot an image in Log-Log axis?

What I want to do is the following: a log-log plot, with areas corresponding to certain categories of flow. Ideally, it would look like the this figure, but with shaded areas.

Currently I am able to determine for each pair of values of x and y, what type of flow it corresponds to. However, I can't plot it over a log-log axis. What I'm gettin looks like this:

The code i'm using is this:

usg=logspace(-1,log10(500),1000); %[m/s]
usl=logspace(-2,log10(50),1000); %[m/s] 

P=findcategory(usl,usg)

figure
h = imagesc(X,Y,P);
h.CDataMapping='direct';
axis xy

where P is a matrix with values from 1 to 8 ( flow categories), where each element is calculated using a pair of elements of usg and usl.

How can I plot this P matrix, in a log-log plot, instead of a linear axis?

Answer 1

[dpb]

...
h = imagesc(usl,usg,P);
hAx=gca;
set(hAx,{'XScale','YScale'},{'log','log'})

[Tomas Carvalho]

Hey,

Thanks, it worked! I was getting some things mixed up in my head, but then I figured it out. I first thought your solution would create another problem, but I was wrong. It is simple and effective. :)

[dpb]

Kewl!

Answer 2

[William Rose]

@Tomas Carvalho,

I canot run your code since I do not have findcategory(). I made usg and usl slightly different lengths to be sure that I my surf plot was oriented the right way. Otherwise it is possible to reverse the x and y coordinates in the plot, without knowing it. I set the edgecolor to none in the surface plot, since if you don't, the black edges will dominate the surface.

usg=logspace(-1,log10(500),101); %[m/s]
usl=logspace(-2,log10(50),100);  %[m/s] 
for i=1:length(usg), for j=1:length(usl)
    P(i,j)=floor(log10(usg(i))+log10(usl(j)))+3; 
end, end
lusg=log10(usg);
lusl=log10(usl);
figure
surf(lusl,lusg,P,'EdgeColor','none');
view(0,90)
xlabel('log_{10} usl'); ylabel('log_{10} usg'); 
colorbar

Try that. It is a start. You still have to get the right labels on the color bar...

[Tomas Carvalho]

Hello,

Your solution would also work! However I prefer to keep the logaritmic scale displayed in the traditional way.

Thank you anyway.