Problem with vertically Concatenating vectors in a function

Question

Joel Schelander 2021-4-27

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/815105-problem-with-vertically-concatenating-vectors-in-a-function

评论： Joel Schelander 2021-4-28

I have a cell array ABC containing three cells each cell contains a 1x1000 double. What I want is to put every double on top of each other in a column vector (nx1).

ABC={1x1000 cell

1x992 cell

1x928 cell);

My function looks like this:

nr=3;
s=1000;
[D]=func(nr,ABC,s);
function D = func(nr,ABC,s)
D = [];
for y =1:nr
    data_length = length(ABC{y});
    for o = 1:data_length 
        G((o-1)*s+1:o*s) = [ABC{y}{o} zeros(1,s-length(ABC{y}{o}))].'; 
    end
    
    D = [D; G.']; 
end
end

My output should be D=2920000x1 double

But my output now is D=3000000x1 double

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Answer 1

Stephen23 2021-4-28

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https://ww2.mathworks.cn/matlabcentral/answers/815105-problem-with-vertically-concatenating-vectors-in-a-function#answer_686810

编辑：Stephen23 2021-4-28

在 MATLAB Online 中打开

Rather than using a loop, a much better use of MATLAB would be to use comma-separated lists:

https://www.mathworks.com/help/matlab/matlab_prog/comma-separated-lists.html

https://www.mathworks.com/matlabcentral/answers/320713-how-to-operate-on-comma-separated-lists

For example:

out = cellfun(@(a)a(:),[ABC{:}],'uni',0);
out = vertcat(out{:})

Or

out = [ABC{:}];
out = [out{:}].'

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Stephen23 2021-4-28

在 MATLAB Online 中打开

"Since every element is a double of 1x1000..."

Lets check that first. Show the output of these commands:

vec = cellfun(@numel,[AAG{:}]);
find(vec~=1000)

Joel Schelander 2021-4-28

@Stephen Cobeldick

Ye its not sorry. Cell 3 looks like this

AAG{3,1}=1x757 double 1x726 double 1x761 double 1x785 double...]

The thing is that each of the doubles have a representing value in another cell array.

AAI{3,1}=[8 11 8 11...]

What I really want to achieve is to plot AAI against AAG.. Thus I need to repeat the values of AAI so that it corresponds to the doubles in AAG.

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Answer 2

DGM 2021-4-27

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/815105-problem-with-vertically-concatenating-vectors-in-a-function#answer_686500

在 MATLAB Online 中打开

% a cell array of numeric row vectors
A = {1:3,10:14,1:5}
% all row vectors concatenated into a col vector
bigcolvec = [A{:}]'

gives

A =
  1×3 cell array
    {1×3 double}    {1×5 double}    {1×5 double}
bigcolvec =
     1
     2
     3
    10
    11
    12
    13
    14
     1
     2
     3
     4
     5