Reformatting a cell array based on the duplicates

Hello, I have a table with two columns and a number of rows (first column contains a variable name and the second column contains its value). The entries of the first column (the variable names) has duplicates, as shown in the example below:

    'x1'    [1]
    'x2'    [2]
    'x3'    [3]
    'x4'    [4]
    'x1'    [2]
    'x4'    [8]
    'x2'    [5]
    'x1'    [5]
    'x4'    [1]

I would like to record the name of the unique variables as the header (without repeatitions) and their values below them. In case of few values, the last value will be repeated just to fill up the cells. From my cell array above I would like to achieve something like this:

    'x1'    'x2'    'x3'    'x4'
    [ 1]    [ 2]    [ 3]    [ 4]
    [ 2]    [ 5]    [ 3]    [ 8]
    [ 5]    [ 2]    [ 3]    [ 1]

How would I achieve this? Any Ideas? Kind regards,

[the cyclist]

Just to clarify ...

Are these values stored in data type table, or data type cell array?

[Johnny]

For this example, they are stored in a cell array. However, the same logic could be applied to tables. As tables can easily be converted to and from cell arrays (at least to my understanding).

Answer 1

[the cyclist]

Here is a straightforward method, if a bit cumbersome. Someone will undoubtedly find a slick one-liner that is better. :-)

A = {
    'x1'    1;
    'x2'    2;
    'x3'    3;
    'x4'    4;
    'x1'    2;
    'x4'    8;
    'x2'    5;
    'x1'    5;
    'x4'    1
    }

[uniqueA,~,jj] = unique(A(:,1));
numberUniqueA = numel(uniqueA);

counts = histcounts(jj,[unique(jj); Inf]);

B = cell(max(counts)+1,numberUniqueA);

B(1,:) = uniqueA';

for ni = 1:numberUniqueA
   indexToThisA = (ni==jj);
   numberThisA = sum(indexToThisA);
   B(2:numberThisA+1,ni) = A(indexToThisA,2);
end

This will actually leave empty cell elements, instead of replicating. Is that OK? If not, then it is also easy to just find the empty cells and fill those in.

[Johnny]

Thank you this works fine for me. Kind regards

Answer 2

[Stephen23]

Not quite one line:

>> [U,~,idx] = unique(A(:,1));
>> C = arrayfun(@(n)A(idx==n,2),unique(idx),'Uni',0)';
>> N = max(cellfun('size',C,1));
>> M = cellfun(@(v)[v;repmat(v(end),N-numel(v),1)],C,'Uni',0);
>> Z = [U';[M{:}]]
Z = 
    'x1'    'x2'    'x3'    'x4'
    [ 1]    [ 2]    [ 3]    [ 4]
    [ 2]    [ 5]    [ 3]    [ 8]
    [ 5]    [ 5]    [ 3]    [ 1]

[Johnny]

You are right here, I had made a mistake in my output table in column x2. It should have been like yours here since 5 is duplicated. Sorry for the confusion. Thank you for this CORRECT ANSWER TOO. Regards,