Add first element to a cell array
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Luis Isaac
el 18 de Dic. de 2015
Comentada: Josh
el 4 de Mayo de 2024
Dear,
I would like to add a new element in the first position in an cell array For example if ArrCell={[1],[2],[3],[4],[5]} is the existing cell and [new] is a matrix. I would like to get ArrCell={[new],[1],[2],[3],[4],[5]}
Of course, I can get this result using a temporal cell array and looping over all the elements of the existing one, but the quesion is if there an efficient way to get this result
Thanks in advance,
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Respuesta aceptada
Adam
el 18 de Dic. de 2015
ArrCell = [ { new }, ArrCell ];
should work. I'm not at my machine with Matlab at the moment so can't double-check, but fairly sure that works.
5 comentarios
Adam
el 20 de Mzo. de 2020
ArrCell was a row array. You can't concatenate vertically a scalar and a 5-element row array.
Image Analyst
el 20 de Mzo. de 2020
new = magic(3) % A matrix
ArrCell={[1],[2],[3],[4],[5]} % A cell array
ArrCell = [ { new }, ArrCell ] % Adam uses comma
ArrCell2 = [ { new }; ArrCell ]; % Daniel uses semicolon
new =
8 1 6
3 5 7
4 9 2
ArrCell =
1×5 cell array
{[1]} {[2]} {[3]} {[4]} {[5]}
ArrCell =
1×6 cell array
{3×3 double} {[1]} {[2]} {[3]} {[4]} {[5]}
Error using vertcat
Dimensions of arrays being concatenated are not consistent.
Error in test1 (line 12)
ArrCell2 = [ { new }; ArrCell ];
Más respuestas (2)
Image Analyst
el 18 de Dic. de 2015
But the big question is why are you even using a cell array for that instead of a simple numerical array. Cell arrays are complicated and use a huge amount of overhead. From what you've shown there is no reason to use one. I recommend this instead
Arr = [1,2,3,4,5];
Arr = [new, 1,2,3,4,5]
2 comentarios
Josh
el 4 de Mayo de 2024
appreciate this nudge in a more efficient direction, i fallback on cells arrays out of habit and ease but switching over to numerical arrays where possible...i make animations and cells help when image sizes are changing at least but seem uneccessary when image size is fixed
Fletcher Garrison
el 3 de Feb. de 2021
Editada: Fletcher Garrison
el 3 de Feb. de 2021
You can also use:
Arrcell = {1,2,3,4,5};
new = magic(5);
Arrcell = horzcat(new,Arrcell);
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