MATLAB: How to extract data from a cell array

cell arrayfor loopMATLAB and Simulink Student Suitevectorwhile loop

Hello, it's the first time that i use arrays and I have a series of 3×1 cell arrays, each of them has 3 cells vith a differet numbers of numerical data. I want to use for loop or while loop in order to ectract the three cells and convert them into different 3 vectors:

C={[2.24;2.28;2.31], [0.99;1.44;1.44;1.44;1.44;2.12;2.25;2.48;3.61], [1.86;1.89;1.89;1.89;1.89;1.89;1.89]};

for j=1:length(C)
    x(j)=C{j};
end

at the end I should have:

x1=[2.24;2.28;2.31]

x2=[0.99;1.44;1.44;1.44;1.44;2.12;2.25;2.48;3.61]

x3= [1.86;1.89;1.89;1.89;1.89;1.89;1.89]

Best Answer

Already you have the cells in your desired way.

You can access them using C{1} , C{2}, C{3} .

You need to store them again into X1, X2, X3.

Related Solutions

MATLAB: Concatenate arrays within a loop,

Easy, given any number of arrays in a cell array C. You could use a loop like this, although it is inefficient because the output array is not preallocated:

C = {[1,2],[3,4],...} % cell array of arrays.
A = C{1};
for k = 2:numel(C)
    A = [A;C{k}];
end

Simpler and more efficient would be to concatenate them all at once, without a loop, e.g.:

A = vertcat(C{:})

Whatever you do, do NOT try to access variable names dynamically in a loop! Read this to know why:

https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

Using an array (e.g. a cell array) and indexing is much simpler, neater, much more efficient, less buggy, and easier to debug.

MATLAB: How to extract elements form a vector in order to create an unknown number of sub-vectors

Here is one simple approach based on diff, cumsum, and accumarray:

>> M = [2.24;2.28;2.31;0.99;1.44;1.44;1.44;1.44;2.12;2.25;2.48;3.61;1.86;1.89;1.89;1.89;1.89;1.89;1.89];
>> X = cumsum([true;diff(M(:))<0]);
>> C = accumarray(X,M(:),[],@(v){v});
>> C{:}
ans =
   2.2400
   2.2800
   2.3100
ans =
   0.99000
   1.44000
   1.44000
   1.44000
   1.44000
   2.12000
   2.25000
   2.48000
   3.61000
ans =
   1.8600
   1.8900
   1.8900
   1.8900
   1.8900
   1.8900
   1.8900

You can access the contents of the cell array using indexing:

https://www.mathworks.com/help/matlab/matlab_prog/access-data-in-a-cell-array.html

Using numbered variables is unlikely to be a good approach.

Best Answer

Related Solutions

MATLAB: Concatenate arrays within a loop,

MATLAB: How to extract elements form a vector in order to create an unknown number of sub-vectors

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