Extract specific rows of a cell

Hey everyone

I have a cell A as below and want to extract a matrix form A of specific rows which stored at r from each rows of A for example row number 4 from first row of A and ...

A=  { 90×1 double}    { 90×1 double}    { 90×1 double}
    {101×1 double}    {101×1 double}    {101×1 double}
    {101×1 double}    {101×1 double}    {101×1 double}
    {100×1 double}    {100×1 double}    {100×1 double}
    { 97×1 double}    { 97×1 double}    { 97×1 double}
    { 75×1 double}    { 75×1 double}    { 75×1 double}
    
    r=
    4
    6
    99
    43
    68
    50
    
    

[Akira Agata]

Question for clarification.

Is the cell array A a 2-D (N-by-M) ? or 1-D (1-by-N or N-by-1) ?

If A is a 1-D cell array, you want to extract k-th number from each double array stored in a cell?

For example, if r = 4, you want to extract A{1}(4), A{2}(4), ..., A{N}(4) and make a 1-D double array [A{1}(4), A{2}(4), ..., A{N}(4)] ?

[Majid Mostafavi]

yes

but A{2}(4) give me only second element of first column

Answer 1

[Akira Agata]

OK. Then, to avoid misunderstanding, let's use a simple example.

Say, A is a 1-by-3 cell array and r = 4, as follows:

A = {rand(90,1), rand(101,1), rand(100,1)};
r = 4;

If you write [A{1}(r), A{2}(r), A{3}(r)], then you can extract the 4th element of each cell.

output = [A{1}(r), A{2}(r), A{3}(r)];

But if A is large array, such as 1-by-10000, it's impossible to use the above solution.

In such a case, I would recommend using cellfun function to do the same thing, like this:

output = cellfun(@(x) x(r), A);

I hope this is answering to your question!