How to populate a cell array with vector elements?

I have a cell array consisting of n-number of cells, each of different size. I also have a vector consisting of n-number of elements. I'd like to populate the cells with the corresponding elements from the vector.

1 Comment

Jan
Jan on 4 Jul 2017
Edited: Jan on 4 Jul 2017
Is this a homework question? If it is: Sorry for posting the easy solution. Note that providing it as your solution would be a kind of cheating. If you ask a homework question, clarify this detail such that the answer can be formulated as hints and you have the chance to solve it by your own.

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 Accepted Answer

Jan
Jan on 4 Jul 2017
Edited: Jan on 4 Jul 2017
What have you tried so far? This is easy with a loop:
C = {ones(1, 3); ones(1, 7); ones(1, 5)};
x = [3; 5, 7];
for k = 1:numel(C)
C{k} = C{k} * x(k);
end
There are some alternatives, which might be needed, if this is a homework question. Hint:
index = [1,1,1];
value = 8;
value(index)

More Answers (2)

I have a cell array consisting of n-number of cells
I assume this means:
n = 17;
C = cell(1, n);
But what does this mean:
each of different size.
? A short explanation would avoid to let the readers guess.
I also have a vector consisting of n-number of elements.
Perhaps this is:
x = rand(1, n)
and
I'd like to populate the cells with the corresponding elements from the vector.
might mean:
for k = 1:numel(C)
C{k} = x(k);
end
Or easier:
C = num2cell(x);
Does this help? If not explain what "each of different size" means.

1 Comment

I have a cell array consisting of n-number of cells
Yes, in my case it is 5x1 cell.
each of different size.
I should have written each cell consists of vectors, which have different sizes.
I also have a vector consisting of n-number of elements.
Yes, in my case it is a column vector
Sorry for ambiguity.

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Assuming you want to append the elements of your vector to vectors in the corresponding cells of your cell array:
result = arrayfun(@(c, el) [c{1}, el], yourcellarray, yourvector, 'UniformOutput', false);
The above assumes that the vectors in the cell arrays are row vectors. If they are column vectors, then it's [c{1}; el]

6 Comments

I didn't get the desired result. The statement added an additional element from the vector to each cell. Does it matter if my vector is not a vector but a nx1 matrix?
A nx1 matrix is a vector.
I didn't get the desired result It's very unclear what is your desired result (and for that matter, the starting point). Provide an example of inputs and desired output.
The statement added an additional element from the vector to each cell. Yes, exactly as described in my sentence: "Assuming you want ...".
As Jan says, a nx1 matrix is a vector, a column vector to be precise. The definition of a vector is a matrix whose all dimensions but one have size 1.
I have 5x1 cell "C" with ones vectors in each cell. Each vector has different size (1x50, 1x100 and so on). I have another vector "V" which is a 5x1 column vector (e.g. V = [2;3;4;5;6]. I need to have the values of vector "V" in place of ones (e.g. C{1,1} = [2 2 2 ...2]; C{2,1} = [3 3 3 ... 3] and so on), or to create another cell array, that would have dimensions similar to "C" containing vectors the same size that "C" has filled with values of V.
Thanks.
@Yerzhigit Bapin: Do you see that an answer is much easier now after you have explained the wanted procedure clearly?
OH, that certainly wasn't clear from the initial question.
A one-liner solution:
result = arrayfun(@(c, el) repmat(el, size(c{1})), yourcellarray, yourvector, 'UniformOutput', false);

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