How to vectorize this code?

Question

AKSHAY PUJARI 2020-5-6

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/523352-how-to-vectorize-this-code

编辑： Sindar 2020-5-6

采纳的回答： Sindar

在 MATLAB Online 中打开

I have the following loop.It is needed to improve the performance and hence need to vectorize the loop.Is it possible?

I am facing difficulty in vectorizing due to use of "sum" operator in line 3 and 5.

frequency=randi([0 578],110,1);
axis(:,1)=[-275:5:270];
for k=1:size(frequency,1)
    if axis(k,1)<=0
        cumFrequency(k,1)=sum(frequency(1:k,1));
    elseif axis(k,1)>0
        cumFrequency(k,1)=sum(frequency(k:end,1));
    end
end

Thanks

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Answer 1

Sindar 2020-5-6

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/523352-how-to-vectorize-this-code#answer_430629

编辑：Sindar 2020-5-6

在 MATLAB Online 中打开

frequency=randi([0 578],110,1);
axis=[-275:5:270]';
% get indices where axis is negative
axis_negative = (axis<=0);
% calculate the cumulative sum of frequency
cumFrequency_neg = cumsum(frequency);
% calculate the reverse cumulative sum of frequency
cumFrequency_pos = cumsum(frequency,'reverse');
% insert the forward and reverse sums in the indices according to axis
cumFrequency(axis_negative,1) = cumFrequency_neg(axis_negative);
cumFrequency(~axis_negative,1) = cumFrequency_pos(~axis_negative);