从Matlab中向量的负值的出现中找到中值向量 [英] Find the vector of medians from the occurrences of the negative values of the vector in matlab

问题描述

说我有一个向量

v =[1,2,3,-1,-2,-3,4,5,6,-7,-6,-3,-5,-4,...]

我想制作一个包含负值出现值的向量.

I want to make a vector which consists of the values of the occurrence of negative values.

当指针位于v[4]时，直到最后一个负值v[6]

When the pointer is at v[4] till the last negative value v[6]

下一步，我需要从负值首次出现的向量v中获取中位数

Next step I need to take the median from the vector v of the first occurrences of the negative values

Vm = [-2] % first occurrence

因此，我想对v[10]重复该过程，直到v[13]，然后再次确定中位数.

Accordingly I want to repeat the procedure for v[10] till v[13] and determine the median again.

并将其添加到向量Vm = [-2,-3]中，依此类推.输出应如下所示:vm = [(median(v(4) to v(6)), (median(v(10) to v(13))),...]

And add it up to the vector Vm = [-2,-3] and so on. The output should be like this: vm = [(median(v(4) to v(6)), (median(v(10) to v(13))),...]

因此，在此示例中，向量应如下图所示vm = [-2,-4,...]

So for this example the vector should look like this vm = [-2,-4,...]

推荐答案

v =[1,2,3,-1,-2,-3,4,5,6,-7,-6,-3,-5,-4]; %Given vector
%Start and end of intervals. strfind is applicable on numeric data as well.
pos = [1,v>=0,1];    start = strfind(pos,[1,0]);     last = strfind(pos,[0,1])-1;

n=length(start); %Number of chunks of the negative values
vm = zeros(1,n); %Pre-allocation of vm
for k=1:n
    vm(k) = median(v(start(k):last(k)));  %Finding required vector of medians   
end

如果没有负值，则vm将作为空向量返回.

If there is no negative value, vm will be returned as an empty vector.

^{关于语句"我想制作一个由负值出现的值组成的向量."，看来这不是您的实际目标，但您可以用v(v<0)找到它.}

^{Regarding the statement, "I want to make a vector which consists of the values of the occurrence of negative values.", it seems that it is not your actual goal but you can find that with v(v<0).}

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