How to plot the average of the graphs ?

Hi,

I have plotted a 3 plots on the same axis and now I want to plot the average of these plots. All my three

vectors that have used have different lenghts. I belive that here we need to interpolate. I want to interpolate my YS3, YS4Q and YS 21Q where I want to use common Lattitude values LatCom, however Im confused becuse I'm not able interploate. Im attaching my plots, code and the error that appeares while interpolating. Im new to matlab and kindly asking for your generous support.

% 3 Combine Plots 
P3 = plot(Lat3,YS3, '-r',Lat4Q,YS4Q, '-k',Lat21Q,YS21Q, '-k');
set(P3,{'LineWidth'},{2;1;1});
xlim([-30 30]);
xticks(-30:10:30)
ylim([0 60])
yticks(0:10:50)
grid
box on
ax = gca;
ax.LineWidth = 2;
title('14/01 ~12.20hrs Log +159','FontSize',10)

% Interploate 
LatCom =  [-30: 0.01: 30]';
y1 = interp1(Lat3,YS3, LatCom); % Im getting a erro as shown below

%Sample points must be unique.
%Error in interp1 (line 188)
        %VqLite = matlab.internal.math.interp1(X,V,method,method,Xqcol);

[the cyclist]

It would be helpful if you uploaded the data in a MAT file. You can use the paperclip icon in the INSERT section of the toolbar.

[Vikash Raj]

Hi I have attached the data as 'Sample data' please find attached

Answer 1

[Chunru]

load(websave("SampleData", "https://www.mathworks.com/matlabcentral/answers/uploaded_files/1110305/Sample%20data.mat"))
%whos
P3 = plot(Lat3,YS3, '-r',Lat4Q,YS4Q, '-k',Lat21Q,YS21Q, '-k');
set(P3,{'LineWidth'},{2;1;1});
%xlim([-30 30]);
xticks(-30:10:30)
%ylim([0 20])
yticks(0:10:50)
grid
box on
ax = gca;
ax.LineWidth = 2;
title('14/01 ~12.20hrs Log +159','FontSize',10)

LatCom =  [-30: 0.01: 30]';

% Interpolation requires unique points
[Lat3u, ia] = unique(Lat3); YS3u = YS3(ia);
y1 = interp1(Lat3u,YS3u, LatCom, 'linear', 'extrap');

[Lat4Qu, ia] = unique(Lat4Q); YS4Qu = YS4Q(ia);
y2 = interp1(Lat4Qu,YS4Qu, LatCom, 'linear', 'extrap');

[Lat21Qu, ia] = unique(Lat21Q); YS21Qu = YS21Q(ia);
y3 = interp1(Lat21Qu,YS21Qu, LatCom, 'linear', 'extrap');

ym = (y1+y2+y3)/3;
hold on 
plot(LatCom, ym, 'b', 'LineWidth', 2)

[Vikash Raj]

Thank you very much. Your codes are working well.