convert a matrix in a struct

Question

elisa ewin 2017-3-21

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评论： Guillaume 2017-3-21

采纳的回答： Guillaume

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Hi,

I have a nested struct userTouristicTraj(i).touristicData(j).touristicTraj (attached) and I want to convert it in a matrix. I have used this code:

for i=1:25
    for j=1:size(userTouristicTraj(i).touristicData,2)
         A(i)=userTouristicTraj(i).touristicData(j).touristicTraj
    end
end

but it doesn't do what I want, can you help me? thanks

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Answer 1

Guillaume 2017-3-21

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You haven't attached your data. The following may do what you want:

datasize = numel(userTouristicTraj(1).touristicData);
touristicTraj = zeros(numel(userTouristicTraj), datasize);
for trajidx = 1:numel(userTouristicTraj)  %don't hardcode end of loop when you can ask matlab for the actual value
    assert(datasize == numel(userTouristicTraj(trajidx).touristicData), 'touristicData size is not consistent');
    for dataidx = 1:numel(userTouristicTraj(trajidx).touristicData)
        touristicTraj(trajidx, dataidx) = userTouristicTraj(trajidx).touristicData(dataidx).touristicTraj
    end
end

Note: I'm not sure why you have size(userTouristicTraj(i).touristicData,2) in your code, which implies that the touristicData field is 2D. Yet you only iterate over one dimension. I have assumed that the field is 1D. I have also assumed that touristicTraj is scalar. And of course, all the touristicData fields must be the same size.

If any of these assumptions are broken, the code above won't work.

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elisa ewin 2017-3-21

编辑：elisa ewin 2017-3-21

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I want to create a matrix n x 3: in this matrix I want to put all the values in touristicTraj. For example:

A=[33.502022000000000 -1.176625840000000e+02 1;33.502433000000000 -1.176625010000000e+02 1;34.0383640000000 -118.877949000000 1;34.0394130000000 -118.875812000000 1; all the values in touristicTraj presents in the nested struct
]

Guillaume 2017-3-21

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So you just want to concatenate them vertically, regardless of their index:

touristicTraj = zeros(0, 3);
originalindices = zeros(0, 2);
for trajidx = 1:numel(userTouristicTraj)  
    for dataidx = 1:numel(userTouristicTraj(trajidx).touristicData)
        touristicTraj = [touristicTraj;
                         userTouristicTraj(trajidx).touristicData(dataidx).touristicTraj]; %#ok<AGROW>
        originalindices = [originalindices; 
                           repmat([trajidx, dataidx], size(userTouristicTraj(trajidx).touristicData(dataidx).touristicTraj, 1), 1)]; %#ok<AGROW>
    end
end

I've also created a matrix originalindices which tells you which index of userTouristicTraj and touristicData corresponds to each row of the final array. If you don't need that simply removes the two relevant lines.

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