Error in function interp1: Sample points must be unique.

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Marthe Westerbroek
Marthe Westerbroek 2022-6-29
评论： Star Strider 2022-6-29
I am running multiple patient files in my matlab script. These files are all the same, however, by just one file I get this error:
Error using matlab.internal.math.interp1
Sample points must be unique.
Error in interp1 (line 188)
VqLite = matlab.internal.math.interp1(X,V,method,method,Xqcol);
My script around this error is as following:
tv_interval = tv_before - polyval(coef_tv, time_interval);
rf_interval = rf_before - polyval(coef_rf, time_interval);
ve_interval = ve_before - polyval(coef_ve, time_interval);
ti_interval = ti_before - polyval(coef_ti, time_interval);
te_interval = te_before - polyval(coef_te, time_interval);
new_time = transpose([0:1:time_interval(end)]);
tv_interval = interp1(time_interval, tv_interval,new_time);
rf_interval = interp1(time_interval, rf_interval,new_time);
ve_interval = interp1(time_interval, ve_interval,new_time);
Thanks!

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回答（2 个）

Torsten
Torsten 2022-6-29
编辑：Torsten 2022-6-29
You can use unique() to get rid of duplicate sample points. It will also sort them.
  2 个评论
Marthe Westerbroek
Marthe Westerbroek 2022-6-29
But wont this influence the results? I use this interpolation to calculate the iqr. Can I still do that ?
Torsten
Torsten 2022-6-29
If you use interp1 as
yq = interp1(x,y,xq)
the vector x must contain unique values and must be sorted in descending or ascending order.
Further
min x <= xq <= max x
should be true.
Are these conditions satisfied in your application ?

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Star Strider
Star Strider 2022-6-29
I looked through the code, however I do not see that you ever actually created a timetable object (introduced in R2016b). The best option will likely be to do tthat, and then use the retime function to do the time interpolation (that appears to be what you want to do, although I cannot determine that definitively).
Contents of ‘test_7_newinterval.m’ —
url = 'https://www.mathworks.com/matlabcentral/answers/uploaded_files/1049880/test_7_newinterval.m';
opts = weboptions('ContentType','text');
W = webread(url, opts)
.

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