indexing cell array of arrays

14 visualizzazioni (ultimi 30 giorni)
John Petersen
John Petersen il 9 Ago 2013
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?

Risposta accettata

Evan
Evan il 9 Ago 2013
Modificato: Evan il 9 Ago 2013
cellfun(@(x)x(1:K),C,'uni',0) %Where C is your original cell array
  3 Commenti
Evan
Evan il 9 Ago 2013
No problem!
Evan
Evan il 10 Ago 2013
Modificato: Evan il 10 Ago 2013
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.

Accedi per commentare.

Più risposte (3)

Azzi Abdelmalek
Azzi Abdelmalek il 9 Ago 2013
for k=1:numel(A)
A{k}=A{k}(1:4);
end
  2 Commenti
Jan
Jan il 10 Ago 2013
I still prefer this due to the speed.
Evan
Evan il 10 Ago 2013
Modificato: Evan il 12 Ago 2013
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.

Accedi per commentare.


Azzi Abdelmalek
Azzi Abdelmalek il 9 Ago 2013
If A is your cell array
cellfun(@(x) x(1:k),A,'un',0)

Daniel Shub
Daniel Shub il 9 Ago 2013
Modificato: Daniel Shub il 23 Ago 2013
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 Commenti
John Petersen
John Petersen il 22 Ago 2013
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 il 23 Ago 2013
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.

Accedi per commentare.

Prodotti

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by