Grouping matrix data into variables when they have the same value in the first column

Apologies if this question has been answered somewhere but I have been checking for a while and couldn't find the answer to this specific problem.

I have a matrix of two columns i.e.

{A}   {B}
1      22
1      19
1      15 
5      12 
5      23
5      45 
5      1
5      4
6      12
6      12
6      23
6      9
10     2
10     3   
10     29

Is there a way I can group the data in column B into variables depending on their value in column A? For example in column B I want 22, 19 and 15 grouped together into a variable, i.e. x, as they all have the same value of 1 in column A. I then want 12, 23, 45, 1 and 4 grouped into a variable, i.e. y, as they all have the same value of 5 in column 1 and so on.

However, the issue I have is that there are around 357 different values of A in Column A and I cannot write them all out manually into the code as it will take forever. Is there a way MATLAB can automatically create the 357 new variables I have shown above automatically by finding all the values in column B which have the same value of A and grouping them? I would then like to obtain the mean and sandard deviation for the data in each of the 357 new data sets.

I hope that is clear enough.

Any help would be greatly appreciated.

[Stephen23]

Use a table and these methods:

https://www.mathworks.com/help/matlab/matlab_prog/split-table-data-variables-and-apply-functions.html

https://www.mathworks.com/help/matlab/matlab_prog/split-data-into-groups-and-calculate-statistics.html

Answer 1

[KSSV]

Let A, B be your first and second column.

[C,ia,ib] = unique(A) ;
N = length(C) ; 
iwant = cell(N,1) ; 
for i = 1:N
  iwant{i} = B(ib==i) ;
end

[sgericeb]

Perfect, Thank you!

[sgericeb]

Just another quick question if you don't mind. The code worked and the data is now stored as 'iwant' variables 1 - 357. However, is there a way I can export each of these variables as column vectors and put them in the same file, as columns 1 - 357? At the moment I can only open them individually.

Thanks a lot!

[KSSV]

You see the dimensions of each cell in iwant will e different. You cannot put them into a matrix. If you want to put them into a matrix, you have to pad NaN or zeros to each cell and make a matrix, Is that okay for you?

[sgericeb]

Yes thanks, I undertand the padding. I'm just not sure how to do it for all 357 new column vectors yet to merge them into a new file