MATLAB: Stress strain average unique sample points

Question

Hi,

For my master thesis i have done several tensile and flexural tests. I plotted most of these in matlab to find an average curve out of 5 test samples. For most of the materials this worked fine. Now i get an error that my sample points have to be unique. I manually import my data as collum vectors. So I have one collum vector for strain (STRAIN1-5), and 1 for stress (STDF1-5). How can i now make sure i only have unique values for strain and stress and still have the right values of strain and stress matching each other? I added my code below.

Thank you in advance!

figure
title('ONYX -45°/45°')
xlabel('Strain(%)')
ylabel('Stress (MPa)')
hold on
plot(STRAIN1,STDF1,'Color' ,[0, 0.4470, 0.7410])
hold on
plot(STRAIN2,STDF2,'Color' ,[0.9290, 0.6940, 0.1250])
hold on
plot(STRAIN3,STDF3,'Color' ,[0.4940, 0.1840, 0.5560])
hold on
plot(STRAIN4,STDF4,'Color' ,[0.4660, 0.6740, 0.1880])
hold on
plot(STRAIN5,STDF5,'r')
hold on
xlim([0 8])
ylim([0 100])
Xavg=[0:0.001:8];
Y1avg = interp1(STRAIN1,STDF1,Xavg);
Y2avg = interp1(STRAIN2,STDF2,Xavg);
Y3avg = interp1(STRAIN3,STDF3,Xavg);
Y4avg = interp1(STRAIN4,STDF4,Xavg);
Y5avg = interp1(STRAIN5,STDF5,Xavg);
Y1avg=Y1avg';
Y2avg=Y2avg';
Y3avg=Y3avg';
Y4avg=Y4avg';
Y5avg=Y5avg';
Yavg = mean([Y1avg Y2avg Y3avg Y4avg Y5avg],2); 
plot(Xavg,Yavg,'-.k','LineWidth',2)
hold on

Answer 1

If (x,y) are your data points. Use the following to avoid the error.

[x,idx] = unique(x) ; 
y = y(idx) ; 
yi = interp1(x,y,xi) ;