I have an index vector that I have to change and I want to change the values of them

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Dani Tormo 2013-2-18

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https://ww2.mathworks.cn/matlabcentral/answers/63976-i-have-an-index-vector-that-i-have-to-change-and-i-want-to-change-the-values-of-them

编辑： Dani Tormo 2013-11-13

采纳的回答： Wayne King

在 MATLAB Online 中打开

Hi all!

I have a vector:

v = [1 0 0 1 1]

I got another index vector that says me which of these values have to be changed to 1:

index = [1 5 3]

The result should be:

v = [1 0 1 0 1]

The code to do this with a for is this one:

 for i=1:Nc_needed 
    v(index(i)) = 1;
 end

I know that there are ways to do it in only one line. Anyone knows how?

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Answer 1

Wayne King 2013-2-18

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https://ww2.mathworks.cn/matlabcentral/answers/63976-i-have-an-index-vector-that-i-have-to-change-and-i-want-to-change-the-values-of-them#answer_75530

编辑：Wayne King 2013-2-18

在 MATLAB Online 中打开

   v = [1 0 0 1 1];
   idx = [1 5 3];
   v(idx) = 1;

But that does not give exactly what you said originally because orignally, elements 1,4,and 5 were already ones, so all the above does is set element 3 to a 1.

Another way

   v = zeros(1,5);
   v(idx) = 1;

So the way to do it with one line is create a vector of indices that you want to change -- the indices must be greater than or equal to 1 and less than or equal to the length of the vector, then use that vector to assign the value to "data" vector