find indices in a large array and replace them with zeros

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Konstantinos 2016-8-17

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https://ww2.mathworks.cn/matlabcentral/answers/299893-find-indices-in-a-large-array-and-replace-them-with-zeros

评论： Konstantinos 2016-8-17

I have an index with 10 rows and 301 columns each. I also have a digital signal with 1 X 250,000 elements. The values of the initial index are isolated from the digital signal because they all have a specific characteristic and I used the following code for this:

index1 = zeros(10,151);
index2 = zeros(10,150);
for i = 1:10
    index1(i,:) = signal(peak(i):(peak(i)+150));
    index2(i,:) = signal((peak(i)-150):(peak(i)-1));
end
index = [index2,index1];

Up to this point everything is fine. However, I want to delete that characteristic by replacing all the index values with zeros back at the digital signal. My problem is that the element arrays in the "index", corresponding to the 10 rows, aren't neighbouring. How can I do this? Would it be easier if I make the replacement within the for loop? Thanks in advance.

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Azzi Abdelmalek 2016-8-17

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Answer 1

Thorsten 2016-8-17

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https://ww2.mathworks.cn/matlabcentral/answers/299893-find-indices-in-a-large-array-and-replace-them-with-zeros#answer_232048

在 MATLAB Online 中打开

for i = 1:10
    index1(i,:) = signal(peak(i):(peak(i)+150));
    index2(i,:) = signal((peak(i)-150):(peak(i)-1));
end

Setting the signal to zero at the peak indices:

for i = 1:10
    signal((peak(i)-150):(peak(i)+150)) = 0;
end

Note that you cannot do the replacement in the same for loop, since the peak(i)-150):(peak(i)+150) may overlap, an then you pick up zeros instead of the real signal values.