indexing cell array of arrays

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John Petersen
John Petersen 2013-8-9
I have a cell array with M arrays of [Nx1] elements in each cell. How do I create a cell array with the same M arrays but with the first K elements of each cell?

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采纳的回答

Evan
Evan 2013-8-9
编辑：Evan 2013-8-9
cellfun(@(x)x(1:K),C,'uni',0) %Where C is your original cell array
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Evan
Evan 2013-8-10
编辑：Evan 2013-8-10
Note that, when using implicit functions with cellfun, operation will often be slower than a FOR LOOP would be (this is because cellfun has to do the looping anyway, plus some overhead). So, in cases where you're working with large arrays and/or operation time is quite important, my method above is not ideal.

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更多回答（3 个）

Azzi Abdelmalek
Azzi Abdelmalek 2013-8-9
for k=1:numel(A)
A{k}=A{k}(1:4);
end
  2 个评论
Jan
Jan 2013-8-10
I still prefer this due to the speed.
Evan
Evan 2013-8-10
编辑：Evan 2013-8-12
Yes. I'll make a comment on my answer noting that Azzi's is preferred in all cases except where you want a quick and messy answer.

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Azzi Abdelmalek
Azzi Abdelmalek 2013-8-9
If A is your cell array
cellfun(@(x) x(1:k),A,'un',0)
Daniel Shub
Daniel Shub 2013-8-9
编辑：Daniel Shub 2013-8-23
It is not clear why you have a cell array with each element having Nx1 data, but if all the Nx1 arrays are the same type you can use CELL2MAT. Sticking with the one line answers:
mat2cell(subsref(cell2mat(x), struct('type', {'()'}, 'subs', {{1:K, ':'}})), K, ones(M, 1));
where x is your cell array.
If the M Nx1 arrays are different classes, for example from the output of
data = textscan(fileID,'%s %s %d %f %f');
I would convert my cell array into a structure array with meaningful field names
tempCellMat = cellfun(@(x)mat2cell(x, ones(length(x), 1), 1), data, 'UniformOutput', false);
structArray = cell2struct([tempCellMat{:}], {'Name','dateStr','age','weight','height'}, 2);
You can then do structArray(1:k).
  2 个评论
John Petersen
John Petersen 2013-8-22
Why I have a cell array: I'm using textscan to read in a file with strings, integers and floats on each line. example:
data = textscan(fileID,'%s %s %d %f %f');
Daniel Shub
Daniel Shub 2013-8-23
Ahh, so each of your M arrays of [Nx1] elements is of a potentially different class. This means you cannot use CELL2MAT and my answer will not work.... See my edit.

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