Elevate a single isoline in a contour (2D) plot

Hi.

I have a 2D contour plot in the form of

contour(x,y,z,'LevelStep',2,'Fill','on')

which gives me isolines varying between the values 22 and 48 (13 fill colours in between), with z depending on various input parameters.

What I am trying to do is colour ONE isoline of the value 34 black, while leaving all other lines uncoloured, recognizable only through the fill of the in between values. The contour is supposed to display cost ranges in dependence of two factors. The isoline with the value x represents the profitability limit (all lines with a higher value are not profitable.

Any help would be much appreciated!

Answer 1

[Sven]

Hi Marc,

Is this what you're trying to do?

[x,y,z] = peaks;
z = z*10
figure
[c,h] = contour(x,y,z,'LevelStep',2,'Fill','on')
hold on
[c2,h2] = contour(x,y,z, [34 34], 'Color','k')

I think that since your first call to contour cannot guarantee that there will be a contour exactly at your chosen level of 34, it's probably a good idea to just superimpose another contour at that specific level.

You can adjust colours of your contour(s) via the handles returned in h and h2.

If instead you really want to adjust the colour of the original contours, then you can hack things a little as follows:

[x,y,z] = peaks;
z = z*10;
yourValue = 34;
clf
[c,h] = contour(x,y,z,'LevelStep',2,'Fill','on');
children = get(h,'Children');
for i=1:length(children)
    if any(get(children(i),'FaceVertexCData')==yourValue)
        set(children(i),'EdgeColor','k')
    end
end

Did that help you out?

[Marc Jakobi]

Thanks a lot. The first solution was exactly what I needed.

[Marc Jakobi]

Hi Sven.

Do you know if it is possible to make the line dotted?

Marc

[Sven]

Sure, there's a property of the resulting handle called 'LineStyle' that can be set to various styles (see the plot command for a list of styles):

[x,y,z] = peaks;
z = z*10;
figure
[c,h] = contour(x,y,z,'LevelStep',2,'Fill','on')
hold on
[c2,h2] = contour(x,y,z, [34 34], 'Color','k')
set(h2,'LineStyle',':')