How to extract element of all matrices within a cell array using cellfun?

I need to extract (2,1) i.e. second row and first column element of all matrices within cell array ?

Answer 1

[Image Analyst]

Are all the matrices in the cells the same size? If so, just use cell2mat() and indexing:

[rows, columns] = size(ca{1})
m = cell2mat(ca)
m21 = m(2:rows:end, 1:columns:end)

[NS]

When i ran this , i get error , this possibly due to Nan , how to account for them first

m = cell2mat(CORCOEF)
Error using cat
Dimensions of matrices being concatenated are not consistent.

Error in cell2mat (line 83)
            m{n} = cat(1,c{:,n});

[Image Analyst]

All matrices in your cells are not the same size. Some are a different size than the others.

[NS]

Thanks sir , I got it:)

[Image Analyst]

Of course, you could always use a simple for loop:

output = ones(1, numel(ca));
for k = 1 : numel(ca)
    thisCellsContents = ca{k}; % Extract this one particular cell
    output(k) = thisCellsContents(2, 1);
end

[NS]

Thanks sir, I figured it out.

Answer 2

[Jos (10584)]

This looks like homework to me. Here is a big hint:

Create a function that extracts this for you and use cellfun to apply it to all cells ...

MyFun  = @(M) M(...)

[NS]

MyFun  = @(M) M(2,1)
A(idx) = cellfun(MyFun,C(idx));

C is my cell array having matrices and in some matrices i have Nan too

When i run above code i get

Index exceeds matrix dimensions.

Error in @(M)M(2,1)

I have Nan values too in matrix , how to get them ?

[James Tursa]

The error indicates that some of your matrices do not have a (2,1) element. So you will need to deal with that. Is this not expected? I.e., are all of your matrices supposed to have a (2,1) element? If not, then what do you want for a result?

[NS]

I have checked all elements have 2,1 elements but only a few have Nan in them , so i will not consider those matrices. But how to get 2,1 element from all matrices with some having Nan?

[James Tursa]

The value of the (2,1) element makes no differrence to indexing ... whether it is finite or inf or NaN. You will not get an "index exceeds" error just because the element is NaN. You get the error because there is no (2,1) element. You need to re-check your matrices. What do you get when you run this:

C = your cell array of matrices
min(cellfun(@numel,C))
min(cellfun(@(c)size(c,1),C))

[NS]

Thanks sir , i got it :)

Answer 3

[Ali Nik]

Hi I want to use all nested arrays inside each cell. Thank you for your help His photo is attached.

[Image Analyst]

Not sure how this is an answer to @NS. And when you said "His photo is attached", we're not sure what photo you're talking about or where it is. Certainly NS's photo is not attached to your Answer.

If you have your own question, start a new question and attach your cell array in a .mat file after you read this:

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