Trouble creating an element-wise nested structure: Subscripted assignment dimension mismatch

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monarch 2017-11-19

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评论： monarch 2017-11-19

Below is a sample data set that I am trying to put into a nested structure. Each array is x y z coordinates. I am trying to be able to run some operations in a nested for loop where I can call for each joint do this...then for each frame within each joint do this...

%Joint center locations @ frame 1=[i-1], 2=[i], 3=[i+1] meter
      Hi1 = [.9940 .7967 0]; %Hip joint center at i-1
      Hi2 = [1.0183 .7959 0]; %Hip joint center at i
      Hi3 = [1.0425 .7959 0]; %Hip joint center at i+1
      Ki1 = [1.0997 .5053 0]; %Knee joint center at i-1
      Ki2 = [1.1223 .5042 0]; %Knee joint center at i
      Ki3 = [1.1448 .5039 0]; %Knee joint center at i+1
      Ai1 = [1.2413 .1126 0]; %Ankle joint center at i-1
      Ai2 = [1.2539 .1081 0]; %Ankle joint center at i
      Ai3 = [1.2639 .1037 0]; %Ankle joint center at i+1
      Mi1 = [1.3626 .1001 0]; %Metatarsal center at i
      Mi2 = [1.3732 .0907 0]; %Metatarsal center at i
      Mi3 = [1.3807 .0797 0]; %Metatarsal center at I

My most recent attempt, I tried this to set up the structure:

j(1).f(1) = [1.3626 .1001 0]; %Metatarsal (1) center at i
    j(1).f(2) = [1.3732 .0907 0]; %Metatarsal (1) center at i
    j(1).f(3) = [1.3807 .0797 0]; %Metatarsal (1) center at I

and got the following error: Subscripted assignment dimension mismatch.

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Answer 1

KL 2017-11-19

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Instead of storing 3 vectors for each joints, I'd recommend using a 3x3 matrix. Place it in a structure with more meaningful names. Something like,

 Joints.Hip.Coordinates = [0.9940 0.7967 0;1.0183 .7959 0;1.0425 .7959 0];
 Joints.Knee.Coordinates = [other values]
 Joints.Metatarsal.Coordinates = ...

if you want to do it for different orientations, just create an array of structs on the top level,

 Frame(1).Joints
 Frame(2).Joints

if you want to loop through different frames, you can say

 for fno = 1:numel(Frame)
   Frame(k).Joints.Hips.Coordinates(1,:)
   %and so on
 end

Do you get the idea?

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monarch 2017-11-19

在 MATLAB Online 中打开

Thank you. For the way I need to run these functions, I think I need my joint to be top level rather than my frame...and then be able to cycle through easily. My idea for the nested for loop was something like this:

For j = joint
    %do these operations for frame 2 of this joint
    for i = 1:3
        %do these operations for all frames for this joint
    end
end