Borrar filtros
Borrar filtros

Compare vectors of different lengths using end of shorter one when it ends

3 visualizaciones (últimos 30 días)
Say I have three vectors:
A = 1:10;
B = 1:5;
C = 1:15;
I want to do an operation using A and either B or C, but, when the shorter vector ends, I want to continue the operation using the last value of the shorter one until the longer one ends too. For example, if I want to add them:
A+B = [1+1,2+2,3+3,4+4,5+5,6+5,7+5,8+5,9+5,10+5];
A+C = [1+1,2+2,3+3,4+4,5+5,6+6,7+7,8+8,9+9,10+10,10+11,10+12,10+13,10+14,10+15];
How can I do this efficiently? Note that A is not always the shortest, so I need to identify which one is shorter as part of this. Thanks!

Respuesta aceptada

Scott MacKenzie
Scott MacKenzie el 3 de Mayo de 2023
Someting like this perhaps:
A = 1:10;
B = 1:5;
C = 1:15;
nA = length(A);
nB = length(B);
nC = length(C);
% A + B
if nA < nB
[A repelem(A(end),1,nB-nA)] + B
else
A + [B repelem(B(end),1,nA-nB)]
end
ans = 1×10
2 4 6 8 10 11 12 13 14 15
% A + C
if nA < nC
[A repelem(A(end),1,nC-nA)] + C
else
A + [C repelem(C(end),1,nA-nC)]
end
ans = 1×15
2 4 6 8 10 12 14 16 18 20 21 22 23 24 25
  2 comentarios
Dan Houck
Dan Houck el 3 de Mayo de 2023
I hadn't thought to replicate the last element to bring them up to the same length. How would you do this if you had a cell array of many vectors of different lengths and you want to loop through them?
Scott MacKenzie
Scott MacKenzie el 4 de Mayo de 2023
Editada: Scott MacKenzie el 4 de Mayo de 2023
If the vectors are in a cell array (CA), then something like this would work:
A = 1:10;
B = 1:5;
C = 1:15;
CA = {A; B; C}
CA = 3×1 cell array
{[ 1 2 3 4 5 6 7 8 9 10]} {[ 1 2 3 4 5]} {[1 2 3 4 5 6 7 8 9 10 11 12 13 14 15]}
nA = length(CA{1});
nB = length(CA{2});
nC = length(CA{3});
% A + B
if nA < nB
[CA{1} repelem(CA{1,end},1,nB-nA)] + CA{2}
else
CA{1} + [CA{2} repelem(CA{2}(end),1,nA-nB)]
end
ans = 1×10
2 4 6 8 10 11 12 13 14 15
% A + C
if nA < nC
[CA{1} repelem(CA{1}(end),1,nC-nA)] + CA{3}
else
CA{1} + [CA{3} repelem(CA{3}(end),1,nA-nC)]
end
ans = 1×15
2 4 6 8 10 12 14 16 18 20 21 22 23 24 25
If there are lots of vectors in CA, you could build a loop that includes the logic above to add the elements in the first vector to the elements in each subsequent vector in the cell array.

Iniciar sesión para comentar.

Más respuestas (0)

Categorías

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

Productos


Versión

R2021b

Community Treasure Hunt

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

Start Hunting!

Translated by