How to divide a long vector into several vectors of known length

Dear all,

Is there a way to divide a vector into several vectors of known length? lets say my vector is:

IDX = [1 2 1 3 4 3 1 2 1 35 4 2];

and I want it to be splittet into three vectors, each of length equal to numel(a{k}), which a{k} is:

a{k} = {[3 2 2 1 2]  [2 1 2 2] [1 2 3 ]}

So, the first vector is to be of length 5, the second vector of length 4, and the last vector of length 3.

 I tried the following,  

for k = 1: 3
    if (k ==1)
        idx{k} = IDX(1:numel(a{k})) ;
    else
idx{k} = IDX(numel(a{k-1})+1:numel(a{k-1})+ numel(a{k}))
    end
end

I wish to see this result:

idx{1} = [1 2 1 3 4], idx{2} = [3 1 2 1] and idx{3}=[35 4 2]

but it seems to only retrieve the first two vectors correctly, and the third one just sucks. Any help please?

Answer 1

[Mohammad Abouali]

IDX = [1 2 1 3 4 3 1 2 1 35 4 2 78]; 
a   = {[3 2 2 1 2]  [2 1 2 2] [1 2 3 4]};

% first get the numel(a{k}) as a vector
vectorSizes=cellfun(@(x) numel(x),a)

vectorSizes =

       5     4     4

% now split IDX into the vectors we desired length
IDX_splitted=mat2cell(IDX,1,vectorSizes);

% each element of the cell IDX_splitted contains one of the vectors that you desire.

IDX_splitted{1}

ans =

       1     2     1     3     4

IDX_splitted{2}

ans =

       3     1     2     1

IDX_splitted{3}

ans =

      35     4     2    78

[Negar]

Thank you so much for nice and easy explanation!

[Mohammad Abouali]

you are welcome. ( ghabel nadare ;) )