indexing cell array of arrays

9 visualizaciones (últimos 30 días)
John Petersen
John Petersen el 9 de Ag. de 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?

Respuesta aceptada

Evan
Evan el 9 de Ag. de 2013
Editada: Evan el 9 de Ag. de 2013
cellfun(@(x)x(1:K),C,'uni',0) %Where C is your original cell array
  3 comentarios
Evan
Evan el 9 de Ag. de 2013
No problem!
Evan
Evan el 10 de Ag. de 2013
Editada: Evan el 10 de Ag. de 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.

Iniciar sesión para comentar.

Más respuestas (3)

Azzi Abdelmalek
Azzi Abdelmalek el 9 de Ag. de 2013
for k=1:numel(A)
A{k}=A{k}(1:4);
end
  2 comentarios
Jan
Jan el 10 de Ag. de 2013
I still prefer this due to the speed.
Evan
Evan el 10 de Ag. de 2013
Editada: Evan el 12 de Ag. de 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.

Iniciar sesión para comentar.


Azzi Abdelmalek
Azzi Abdelmalek el 9 de Ag. de 2013
If A is your cell array
cellfun(@(x) x(1:k),A,'un',0)

Daniel Shub
Daniel Shub el 9 de Ag. de 2013
Editada: Daniel Shub el 23 de Ag. de 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 comentarios
John Petersen
John Petersen el 22 de Ag. de 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 el 23 de Ag. de 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.

Iniciar sesión para comentar.

Categorías

Más información sobre Matrix Indexing en Help Center y File Exchange.

Productos

Community Treasure Hunt

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

Start Hunting!

Translated by