Exrapolate values from cell matrix and operations with cell elements

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EldaEbrithil 2020-10-14

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https://ww2.mathworks.cn/matlabcentral/answers/613921-exrapolate-values-from-cell-matrix-and-operations-with-cell-elements

评论： Ameer Hamza 2020-10-15

Hi all

i have a cell matrix where each cell is nx3 double. Assuming you have the coordinates ( [y k] where y and k are arrays )of the cells that interest me, I want, from these selected cells, to extrapolate only the first of the three columns.

How can be done?

Thank you for the help

Regards

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Answer 1

Ameer Hamza 2020-10-14

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编辑：Ameer Hamza 2020-10-14

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I am not sure about the point related to extrapolation. If you just want to extract the first column of selected cells, then you can try this

C; % cell matrix
y; % row index of selected cells
k; % column index of selected cells
idx = sub2idx(size(C), y, k);
C_selected = C(idx);
first_columns = cellfun(@(x) {x(:,1)}, C_selected);

if all columns have same length then you can create a matrix

first_columns = [first_columns{:}];

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EldaEbrithil 2020-10-15

Thanks you very much Ameer!!

I have also another question: consider two array A and B with the same number of cell. Each cell has different length, i want to perform operations with the elements content inside each cell so which of the following expressions is better?

C{i}=A{i}/{B{i}

C{i}=A{i}./{B{i}

C{:,i}=A{:,i}./{B{:,i}

Ameer Hamza 2020-10-15

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It depends on what you are trying to do. / is used for "matrix division", whereas ./ is used for element-wise division. If corresponding cells of A and B have an equal number of elements, then I think you want to use

C{i}=A{i}./{B{i}

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