Fill area between contour levels

Hi everyone!

I have a simple contourplot with some levels. I want to fill with a solid color (grey) the area between two levels (0 and 4).

Thanks in advance

Here's my code:

close all;
clear;
clc;

dati=xlsread('../isoFAMTEMmono.xlsx');

%x data
luce = dati(2:14,1);
%y data
sp_arco = dati(1,2:7);
%z data
famTEM1_1 = dati( 2:14, 2:7 );

figure;
hold on
[C1,h1]=contour(sp_arco,luce,famTEM1_1,'k','LevelList',0:2:20,'ShowText','on','LineWidth',1.2);
[C2,h2]=contour(sp_arco,luce,famTEM1_1,'k','LevelList',20:5:50,'ShowText','on','LineWidth',1.2);
[C3,h3]=contour(sp_arco,luce,famTEM1_1,'k','LevelList',50:10:100,'ShowText','on','LineWidth',1.2);

xlabel('Spessore Arco');
ylabel('Luce');
title(Titolo1A,'FontSize',10)
clabel(C1,h1,'LabelSpacing',500);
clabel(C2,h2,'LabelSpacing',500);
clabel(C3,h3,'LabelSpacing',500);

xlim([0.3,1.5]);
ylim([3,15]);
xticks(0.3:0.1:1.5);
yticks(0:1:15);
hold off

[Alvise Giora]

Thank you all! I've figured out how to fill specific level using caxis and custom colormap

[darova]

Can you post it as an answer? I can't believe it

[Alvise Giora]

    close all;
    clear;
    clc;
    dati=xlsread('../isoFAMTEMmono.xlsx');
    %x data
    luce = dati(2:14,1);
    %y data
    sp_arco = dati(1,2:7);
    %z data
    famTEM1_1 = dati( 2:14, 2:7 );

cmap=[0.8 0.8 0.8 
1 1 1];

    figure;
    hold on
    [C1,h1]=contourf(sp_arco,luce,famTEM1_1,'k','LevelList',0:2:20,'ShowText','on','LineWidth',1.2);
    [C2,h2]=contourf(sp_arco,luce,famTEM1_1,'k','LevelList',20:5:50,'ShowText','on','LineWidth',1.2);
    [C3,h3]=contourf(sp_arco,luce,famTEM1_1,'k','LevelList',50:10:100,'ShowText','on','LineWidth',1.2);
    xlabel('Spessore Arco');
    ylabel('Luce');
    title(Titolo1A,'FontSize',10)
    clabel(C1,h1,'LabelSpacing',500);
    clabel(C2,h2,'LabelSpacing',500);
    clabel(C3,h3,'LabelSpacing',500);
    colormap(cmap);
    caxis([0 8]);
    xlim([0.3,1.5]);
    ylim([3,15]);
    xticks(0.3:0.1:1.5);
    yticks(0:1:15);
    hold off

[darova]

smart!

Answer 1

[the cyclist]

I am hoping for your sake that there is a better way than this (possibly using the Image Processing Toolbox?), but here is one way.

% Create the figure. Turn on "hold", to superpose the patch afterward
figure
hold on

% Create a simple contour plot, and output the contour information
M = contour(peaks(3));

% Extract the level information for two of the contours.
% This step is manual and annoying. It is *possible* to automate this,
% but I think it would be pretty intricate. Not worth the effort if you
% only need to do this once.
% See documentation of contour output M, for how the info is stored.
% (https://www.mathworks.com/help/matlab/ref/contour.html#mw_27cd6c94-d861-4e0a-837c-0a19f2574186)
level1 = M(:,26:30);
level2 = M(:,32:36);

% Combine the x and y coordinates of the two levels.
x = [level1(1,:) level2(1,:)];
y = [level1(2,:) level2(2,:)];

% Define a light gray color
gray = [0.8 0.8 0.8];

% Fill the patch
fill(x,y,gray)

% Cover up the line that connects the final vertex back to the initial one,
% using the same color
line([x(1) x(end)],[y(1) y(end)],'Color',gray)

[Alvise Giora]

Thank you for the response. I've understand what you did. Unfortunately i have a lot of plots and the levels aren't constant.

I have tried also to use contourf and custom colormaps. Is there a way to define specific colors for defined levels?

[Maleen Wijeratna Kidiwela]

issue i have with this is selecting levels i want from

level1 = M(:,26:30);

level2 = M(:,32:36);

Answer 2

[darova]

Here is an idea:

• plot all your contours

• fill external contour you want

[~,h1] = contourf(X,Y,Z,[1 1],'edgecolor','none');
h11 = get(h1,'children');
set(h11,'FaceColor',[1 1 1]*0.8)

• fill interior contour with white color

[~,h2] = contourf(X,Y,Z,[3 3],'edgecolor','k');
h22 = get(h2,'children');
set(h22,'FaceColor',[1 1 1])

QUESTION:

Don't know why some contours lose their colors after i tried to change Z coordinate (because of mixing colors)

set(h22,'ZData',Z*0+0.1)

Script i used

[X,Y,Z] = peaks(20);
% surf(X,Y,Z,'facecolor','none','edgeColor',[1 1 1]*0.7)
% hold on
[~,h] = contour(X,Y,Z,-5:2:5);
set(h,'linewidth',2);
% hold off

hold on
[~,h1] = contourf(X,Y,Z,[1 1],'edgecolor','none');
[~,h2] = contourf(X,Y,Z,[3 3],'edgecolor','k');
hold off

h11 = get(h1,'children');
h22 = get(h2,'children');
set(h11,'FaceColor',[1 1 1]*0.8)
set(h22,'FaceColor',[1 1 1])
set(h22,'ZData',Z*0+0.1)
view(3)
box off
grid on
zlim([-1 1])