Index exceeds matrix dimensions

I've compared my script to my classmates and have it exactly the same, yet I keep getting an error code and she is not.

The script:

shoxdata = filtdata(:, strmatch('RSHO_X', labels));
shoydata = filtdata(:, strmatch('RSHO_Y', labels));
hipxdata = filtdata(:, strmatch('RGT_X', labels));
hipydata = filtdata(:, strmatch('RGT_Y', labels));
knexdata = filtdata(:, strmatch('RKNE_X', labels));
kneydata = filtdata(:, strmatch('RKNE_Y', labels));
ankxdata = filtdata(:, strmatch('RANK_X', labels));
ankydata = filtdata(:, strmatch('RANK_Y', labels));
heexdata = filtdata(:, strmatch('RHEE_X', labels));
heeydata = filtdata(:, strmatch('RHEE_Y', labels));
metxdata = filtdata(:, strmatch('RMET_X', labels));
metydata = filtdata(:, strmatch('RMET_Y', labels));
hipangle = [];
kneeangle = [];
ankangle = [];
startframe = 1;
endframe = length(shoxdata);
frame = startframe;
while frame <= endframe
footseg = 180 + atand((heeydata(frame)-metydata(frame))/(heexdata(frame)-metxdata(frame)));
trunkseg = atan2d((shoydata(frame)-hipydata(frame)),(shoxdata(frame)-hipxdata(frame)));
thighseg = atan2d((hipydata(frame)-kneydata(frame)),(hipxdata(frame)-knexdata(frame)));
shankseg=atan2d((kneydata(frame)-ankydata(frame)),(knexdata(frame)-ankxdata(frame)));
hipangle = [hipangle:(thighseg-trunkseg)];
kneeangle = [kneeangle:(thighseg-shankseg)];
ankangle = [ankangle:(footseg-shankseg-90)];
frame = frame+1;
end
figure(1)
subplot(3,1,1)
plot(hipangle(151:265))
ylabel('Hip Angle')
subplot(3,1,2)
plot(kneeangle(151:265))
ylabel('Knee Angle')
subplot(3,1,3)
plot(ankangle(151:265))
ylabel('Ankle Angle')

[Star Strider]

In the future, please format your code by highlighting it, then using the [{}Code] button to format it.

Answer 1

[Star Strider]

If her code runs and yours doesn’t, yours and hers aren’t the same.

I suspect the problem may be here:

hipangle = [hipangle:(thighseg-trunkseg)];
kneeangle = [kneeangle:(thighseg-shankseg)];
ankangle = [ankangle:(footseg-shankseg-90)];

The colon (link) operator by default creates an ascending series with a default increment of 1. If the calculations in parentheses are less than ‘hipangle’, ‘kneeangle’, or ‘ankangle’ on the right-hand-side in the three assignments, the result will be an empty element. So first, check the sizes of those variables. I believe the problem will be readily apparent. That would throw the error in your plot calls.

This may be what you want to do:

hipangle = [hipangle  (thighseg-trunkseg)];
kneeangle = [kneeangle  (thighseg-shankseg)];
ankangle = [ankangle  (footseg-shankseg-90)];

Here, I replaced the colon (:) with spaces (although commas (,) would work as well). See if that works in your code.

[Andrew Wentz]

That worked!! Thank you so much!

[Star Strider]

As always, my pleasure!

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