How do I add values to a vector?

Question

Gabriel Aguirre 2023-12-12

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2059764-how-do-i-add-values-to-a-vector

评论： Voss 2023-12-12

How do I add values to a vector? I have the vector gdl_off = [1,2,14] and the vector X with 11 positions. I want the values in the positions specified by gdl_off to be 0, but if I use X(gdl_off,:) = 0, it only replaces the existing values.

gld_off = [1,2,14];

X = Kg_cut\F_cut;

X(gdl_off,:) = 0

but i have this

0

0.000248324742039762

-0.000614863156129983

0.000173205080756888

-0.000715692193816531

0.000207846096908266

-0.000735692193816530

9.80854194740139e-05

-0.000614863156129983

0.000346410161513776

0

and my original X is

0.000138564064605510

-0.000735692193816531

0.000248324742039762

-0.000614863156129983

0.000173205080756888

-0.000715692193816531

0.000207846096908266

-0.000735692193816530

9.80854194740139e-05

-0.000614863156129983

0.000346410161513776

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jessupj 2023-12-12

在 MATLAB Online 中打开

if you only want it to replace values, but NOT add new elements to the vector if you specify assignment to non-existing entries, then limit the assignment indices to the current length of the vector:

x( intersect(gld_off,1:numel(x)) ,:) = 0

otherwise, i'm not sure what you're after or what you're expecting.

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Answer 1

Voss 2023-12-12

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https://ww2.mathworks.cn/matlabcentral/answers/2059764-how-do-i-add-values-to-a-vector#answer_1370164

在 MATLAB Online 中打开

If you want to insert a zero element at each of the locations specified by gld_off, in turn, you can do this:

X = [0.000138564064605510;-0.000735692193816531;0.000248324742039762;-0.000614863156129983;0.000173205080756888;-0.000715692193816531;0.000207846096908266;-0.000735692193816530;9.80854194740139e-05;-0.000614863156129983;0.000346410161513776];
gld_off = [1,2,14];
for ii = 1:numel(gld_off)
    X = [X(1:gld_off(ii)-1); 0; X(gld_off(ii):end)];
end
disp(X)
   1.0e-03 *

         0
         0
    0.1386
   -0.7357
    0.2483
   -0.6149
    0.1732
   -0.7157
    0.2078
   -0.7357
    0.0981
   -0.6149
    0.3464
         0

However, the following is more efficient when you need to insert a large number of elements:

X = [0.000138564064605510;-0.000735692193816531;0.000248324742039762;-0.000614863156129983;0.000173205080756888;-0.000715692193816531;0.000207846096908266;-0.000735692193816530;9.80854194740139e-05;-0.000614863156129983;0.000346410161513776];
gld_off = [1,2,14];
NX_new = numel(X)+numel(gld_off);
X_new = zeros(NX_new,1);
X_new(setdiff(1:NX_new,gld_off)) = X;
X = X_new;
disp(X)
   1.0e-03 *

         0
         0
    0.1386
   -0.7357
    0.2483
   -0.6149
    0.1732
   -0.7157
    0.2078
   -0.7357
    0.0981
   -0.6149
    0.3464
         0