How to access/manipulate data from cell arrays?
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So I have the code bleow which sovles an ODE 1000 times with random variables. The result is a 1000 by 1 cell array, the contents of which are all XX by 2 numeric arrays (column 1 solves x(1), column 2 solves x(2)). What I would like to produce is an XX by 1000 numeric array, where my 1000 columns would be comprised of all column 2 data from the numeric arrays nested in my cell array. Is this possible? I've looked through the Cell Arrays and Multilevel Indexing to Access Parts of Cells pages, and haven't been able to find what I'm looking for. Any help would be appreciated.
n = 1000;
result = cell(n,1);
for k=1:n
tspan=[1 7];A0=rand;P0=rand;g=rand;p=rand;B=rand;
[t,x] = ode45(@(t,x) [-g*x(1) + p*x(1); -x(1)*x(2)+ B*x(2)], tspan, [A0 P0]);
result{k} = x;
end
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Accepted Answer
Adam Danz
on 3 Jun 2019
Edited: Adam Danz
on 3 Jun 2019
This extracts column 2 data from all elements of the cell array and arranges it in a row within a cell array as you described.
C = cellfun(@(x)x(:,2),result,'UniformOutput', false)';
Here's how to put that into a padded array
% how much padding is needed per cell?
maxLen = max(cellfun(@(x)size(x,1),result)); %max length
padNum = maxLen - cellfun(@(x)size(x,1),result);
% get the col 2 vals and pad them
C = cellfun(@(x)x(:,2),result,'UniformOutput', false);
Cpad = cellfun(@(x,p)padarray(x,p,NaN,'post'),C,num2cell(padNum),'UniformOutput',false);
% Put them into a matrix
M = cell2mat(Cpad');
4 Comments
Adam Danz
on 3 Jun 2019
If they were all the same size, it would be as easy as
C = cellfun(@(x)x(:,2),result,'UniformOutput', false)';
cell2mat(C)
More Answers (1)
madhan ravi
on 3 Jun 2019
Edited: madhan ravi
on 3 Jun 2019
result{k} = x(:,2);
To produce a numeric matrix you need to append with nan or zeros at the end.
M=max(cellfun('prodofsize', result));
Desired=cell2mat(cellfun(@(x) [x;zeros(M-numel(x),1)], result,'un', 0))
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