Matlab: colorbar of contourplot only for specified contour levels
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I plotted a contour plot in Matlab with data stored in in A, B and C.
contourf(A,B,C,'LineColor','none')
The data stored in C contains values which are 1, 45, 600 and 1000. So the contour plot has only 4 different contour levels. So far as good.
No my issue: I want to show a colorbar with only the 4 contour levels and only the particular colors for 1, 45, 600 and 1000. Therefore I used the code:
colorbar('Ticks',[1,45,600,1000]);
Unfortunatly, Matlab is now plotting a gradient colorbar from 0 to 1000 (gradient colors) and shows only the ticks defined in the code above at the position between 0 and 1000.
How can I get a colorbar showing only the 4 contour levels without a colorgradient?
Thanks in advance!
1 commentaire
Dyuman Joshi
le 19 Oct 2023
Could you share the data you are working with? Use the paperclip button to attach.
Réponses (2)
Florian Bidaud
le 19 Oct 2023
Modifié(e) : Florian Bidaud
le 19 Oct 2023
f = figure(1);
c = colorbar;
f.Children(2).CLim = [0 1000];
c.Ticks = [2 45 600 1000];
color_array = [0 0 1; 0 1 0; 1 1 0; 1 0 0];
f.Colormap = [repmat(color_array(1,:),c.Ticks(1)+1,1); repmat(color_array(2,:),c.Ticks(2)-c.Ticks(1)-1,1); repmat(color_array(3,:),c.Ticks(3)-c.Ticks(2),1); repmat(color_array(4,:),c.Ticks(4)-c.Ticks(3),1)];
You can choose the colors with the color_array, with 1x3 vectors of values from 0 to 1.
Then you can plot your contour :)
EDIT: if you know you have only these four values, you could even do something like this:
f = figure(2);
c = colorbar;
f.Children(2).CLim = [0 1000];
c.Ticks = [2 45 600 1000];
c.TickDirection = 'none';
color_array = [0 0 1; 0 1 0; 1 1 0; 1 0 0];
f.Colormap = [repmat([0 0 0],max(0,c.Ticks(1)-10),1); repmat(color_array(1,:),18,1); repmat([0 0 0],max(0,c.Ticks(2)-c.Ticks(1)-20),1); repmat(color_array(2,:),18,1); repmat([0 0 0],max(0,c.Ticks(3)-c.Ticks(2)-20),1); repmat(color_array(3,:),18,1); repmat([0 0 0],max(0,c.Ticks(4)-c.Ticks(3)-12),1); repmat(color_array(4,:),18,1)];
2 commentaires
Florian Bidaud
le 19 Oct 2023
Modifié(e) : Florian Bidaud
le 19 Oct 2023
Try ploting the contour before everything else like this, and with the right levels.
f = figure(2);
contour([45 45 45; 45 600 1000; 1000 45 2;1000 1000 0; 1000 500 400],[2 45 600 1000])
c = colorbar;
f.Children(2).CLim = [0 1000];
c.Ticks = [2 45 600 1000];
c.TickDirection = 'none';
color_array = [0 0 1; 0 1 0; 1 1 0; 1 0 0];
f.Colormap = [repmat([0 0 0],max(0,c.Ticks(1)-10),1); repmat(color_array(1,:),18,1); repmat([0 0 0],max(0,c.Ticks(2)-c.Ticks(1)-20),1); repmat(color_array(2,:),18,1); repmat([0 0 0],max(0,c.Ticks(3)-c.Ticks(2)-20),1); repmat(color_array(3,:),18,1); repmat([0 0 0],max(0,c.Ticks(4)-c.Ticks(3)-12),1); repmat(color_array(4,:),18,1)];
Star Strider
le 19 Oct 2023
I cannot get the ticks exactly where I would like them, even doing my best to interpolate them.
Perhaps this —
[X,Y,Z] = peaks(20); % Create Data
[z1,z2] = bounds(Z(:));
Z = (Z-z1*0.95) * 2E+2;
Lvls = [1 45 600 1000]; % Define Levels
figure
% contour(X, Y, Z, Lvls, 'ShowText',1)
contourf(X, Y, Z, Lvls, 'ShowText',1)
colormap(turbo(numel(Lvls)))
hcb = colorbar;
tx = hcb.Ticks;
txv = interp1([0 1],[min(tx) max(tx)],(0:numel(Lvls)-1)/(numel(Lvls)-1)); % Interpolate Tick Positions
hcb.Ticks = txv;
hcb.TickLabels = Lvls;
.
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