Matrix storage and extraction inside a cell or a strucutre array.

How do I store matrix and extract matrix from a cell or a structure by using a for loop??????

a=[1 2 3;4 5 6;7 8 9]

b=[11 12 13;14 15 16;7 8 19]

c=[121 212 213;14 15 16;27 28 29]

I created an cell array by following method

d=[{a},{b},{c}]

Suppose I have to retrive b from d. How do I retrive it????

Suppose a,b,c are images represented in matrix form. I need to know if these matrix can be stored in a structure or in a cell array by using a for loop and later retrived by a for loop.

[Stephen23]

Simpler:

d = {a,b,c};

"Suppose I have to retrive b from d. How do I retrive it????"

Basic indexing:

b = d{2};

https://www.mathworks.com/help/matlab/matlab_prog/access-data-in-a-cell-array.html

Answer 1

[Ameer Hamza]

You can use curly bracket indexing with cell arrays. To extract the content of the second element from cell array 'd', run

b = d{2};

Also, note that you should never create a related variable with different names. So instead of creating a, b, c, and then using for loop to create cell array or struct. It is better to create the cell array to being with. There are ways to create cell array using for-loop using eval(), but it is highly unrecommended in MATLAB. See the reason here: https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

[Ron Herman]

Thank you Stephen and Ameer for the reply . It helped me.

I have some other doubts too.

Cant we create a blank structure or an empty structure???

Then store data into it and later use indexing to retrive data???

[Ameer Hamza]

Yes you can do that. For example

s = struct(); % empty struct

s(1).a = rand(1,10); % create field a in struct
s(2).b = rand(2,20); % create field b and assign value to second
                     % element in struct array

However, all the elements in the struct array will have the same field names. If you don't assign a value to a specific field of an element of struct array, then It will be an empty vector. Run the above code to see the value of fields 'a' and 'b' for both elements of struct array 's'.