Extract specific rows of a cell

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Majid Mostafavi
Majid Mostafavi 2020-1-25
编辑： Akira Agata 2020-1-25
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
  2 个评论
Akira Agata
Akira Agata 2020-1-25
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
Majid Mostafavi 2020-1-25
yes
but A{2}(4) give me only second element of first column

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回答（1 个）

Akira Agata
Akira Agata 2020-1-25
编辑：Akira Agata 2020-1-25
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!

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