Reformatting a cell array based on the duplicates

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Johnny 2017-2-6

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https://ww2.mathworks.cn/matlabcentral/answers/323611-reformatting-a-cell-array-based-on-the-duplicates

评论： Johnny 2017-2-6

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,

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the cyclist 2017-2-6

Just to clarify ...

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

Johnny 2017-2-6

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).

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Answer 1

the cyclist 2017-2-6

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https://ww2.mathworks.cn/matlabcentral/answers/323611-reformatting-a-cell-array-based-on-the-duplicates#answer_253551

在 MATLAB Online 中打开

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.

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Johnny 2017-2-6

Thank you this works fine for me. Kind regards

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Answer 2

Stephen23 2017-2-6

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/323611-reformatting-a-cell-array-based-on-the-duplicates#answer_253584

编辑：Stephen23 2017-2-6

在 MATLAB Online 中打开

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]

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Johnny 2017-2-6

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,

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