MATLAB: How to create a matrix from a vector using specified values

loopsmatrix manipulation

I have a column of hip angle data from a treadmill walking trial (roughly 1 min) with a length of 12113 elements. I have identified heel strikes in a separate vector of data that has a length of 55 elements (55 heel strikes). I want to create a matrix where each column is hip angle data between successive elements of the heel strike vector (each column represents one stride). I have tried for loops and while loops, but nothing has worked.

I was able to create a single column of data representing one stride (using the commands below), but I need to get all 54 strides into a matrix. Do any of you have suggestions to how I can create the matrix?

i = 1;
LHIP(:,1) = LHIP_Angles(LHEE_Strikes(i):LHEE_Strikes(i+1));

Thanks in advance.

Best Answer

John - since it is unlikely that each stride has the same number of hip angles, you may want to use a cell array to store the data. Try the following

 LHIP = cell(1,length(LHEE_Strikes)-1);
 for k=1:length(LHEE_Strikes)-1
     LHIP{k} = LHIP_Angles(LHEE_Strikes(k):LHEE_Strikes(k+1));
 end

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This is a job for interp1:

Signal     = rand(1, 1000);  % Test data
HeelStrike = 72;
ToeOff     = 413;
Contact    = Signal(HeelStrike:ToeOff);
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Now the ground contact phase is normalized to 101.

If this is a bottleneck in your code, use FEX: ScaleTime:

ContactN = ScaleTime(Signal, HeelStrike, ToeOff, 101);

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Best Answer

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