How to get all possible combinations of data in a cell?

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Jethro G
Jethro G 2017-2-10
评论： José-Luis 2017-2-10
I have a cell with 4 rows that contains a number of data in this format:
A, B, C, D
E, F,
1, 2, 3, 4
5, 6, 7
How can i get all possible combinations (one from each row)? For example AE15, AF15, and so on..
  2 个评论
José-Luis
José-Luis 2017-2-10
编辑：José-Luis 2017-2-10
What have you tried so far? This looks like a homework question.
Hints: The ugly solution would involve nested loops. A bit better would be to look into ndgrid(). bsxfun() could probably be used. Etc...
Jethro G
Jethro G 2017-2-10
Hah I wish I was still at the age where I had homework to do. I don't have an issue with looping everything for each row manually i can do that. The problem is that I'm trying to find a method that executes the required number of loops irregardless of the size of cell that the user provides.
IE whether the user gives a cell with 10 rows or 3 rows

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回答（1 个）

José-Luis
José-Luis 2017-2-10
编辑：José-Luis 2017-2-10
data = {{'A', 'B', 'C', 'D'}; ...
{'E','F',};...
{1, 2, 3, 4};...
{5, 6, 7}};
cell_size = cellfun(@(x) size(x,2) ,data);
tot_elements = cell_size' * cell_size;
[I,J,K,L] = ind2sub(cell_size',1:tot_elements);
result = [cell2mat(data{1}(I)'), cell2mat(data{2}(J)'), char([data{3}{K}]+48)', char([data{4}{L}]+48)'];
EDIT Going out of my way to avoid loops and having it work for variable-size input:
data = {{'A', 'B', 'C', 'D'}; ...
{'E','F',};...
{1, 2, 3, 4};...
{5, 6, 7}};
cell_size = cellfun(@(x) size(x,2) ,data);
tot_elements = prod(cell_size);
%Turning data into a cell array of character array
is_a_number = cellfun(@(x) isnumeric(cell2mat(x)),data);
data(is_a_number) = cellfun(@(x) {char(cell2mat(x) + 48)},data(is_a_number));
data(~is_a_number) = cellfun(@(x) {cell2mat(x)},data(~is_a_number));
%Avoiding ind2sub, convoluted way of obtaining the indexes
idx = (1:numel(data));
idx_array = bsxfun(@(x,y) ceil( (mod(x-1,prod(cell_size(1:y)))+1) ./ ...
(prod(cell_size(1:y)) / cell_size(y) ) ),...
(1:tot_elements)', idx);
%Finally getting the results based on idx_array
result = cell2mat(cellfun(@(x) {data{x}(idx_array(:,x))}, num2cell(idx))')';
Not an (explicit) loop in sight but not pretty. Not very maintainable either. I won't directly understand this if I look at it down the line. Loops in this case would be clearer, IMO.
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Jethro G
Jethro G 2017-2-10
编辑：Jethro G 2017-2-10
Thank you very much. I guess the only thing that's left for me now is instead of defining IJKL (which only works for 4-row cells), to generete those depending on the number of rows in the cell that the user provides, but i'm sure i can figure that out! Thanks a lot!

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