how to convert cell array of struct to matrix

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ORR 2020-8-18

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编辑： Stephen23 2020-8-18

Hey,

I have cell array, each contain struct.

data{1}.time=[1:10]

data{1}.pos=[1:10]

data{2}.time=[5:100]

data{2}.pos=[1:96]

i would like to create a time matrix and a pos matrix.

the matrix can be sparse or filled with nan where the size do not match tha max length of the time/pos vector.

so far i was using:

for n=1:2

time(1:length(data{n}.time),n)=data{n}.time

end

thanks

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Stephen23 2020-8-18

编辑：Stephen23 2020-8-18

Note that square brackets are a concatenation operator, and are superfluous in this code: [1:10] because the colon operator already returns a vector, which you then concatenate with ... nothing. Get rid of the brackets, they literally do nothing**.

https://www.mathworks.com/matlabcentral/answers/35676-why-not-use-square-brackets

** except mislead experienced MATLAB users who know that they are a concatenation operator, and mislead beginners who believe that they are some kind of required "list" operator (which MATLAB does not have).

ORR 2020-8-18

thanks

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Answer 1

Stephen23 2020-8-18

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https://ww2.mathworks.cn/matlabcentral/answers/581018-how-to-convert-cell-array-of-struct-to-matrix#answer_481478

编辑：Stephen23 2020-8-18

在 MATLAB Online 中打开

Rather than creating a cell array of scalar structures, you should create one single structure array:

>> S(1).time = 1:10; % I also removed the superfluous square brackets
>> S(1).pos  = 1:10;
>> S(2).time = 5:100;
>> S(2).pos  = 1:96;

Then you can trivially process all of the field data with one simple comma-separated list, e.g.:

>> Vtime = [S.time];
>> Vpos  = [S.pos];

And you can use this to easily create the required matrix by downloading Jos's excellent padcat:

>> Mtime = padcat(S.time);
>> Mpos  = padcat(S.pos);

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Stephen23 2020-8-18

编辑：Stephen23 2020-8-18

"...while my data is 1X2 cell. each cell contain the struct."

Which is why at the end of my answer I showed how you can convert the cell array of structures to one structure array.

Did you try it?

Don't worry, that conversion will be quite efficient because it does not copy your data arrays, just creates a small list of references to them in memory.

ORR 2020-8-18

yes.

dimentions of matrix being concatenated are not consistent

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