Find the vector of medians

say I have a vector

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

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

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

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

Vm = [-2] % first occurrence

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

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))),...]

so for this example the vector should look like this vm = [-2,-5,...]

Can you please help me out?

Thanks in advance

[Stephen23]

@Jayanta Deb: please edit your question and show the expected output.

[Jayanta Deb]

I have edited the question. You can see.

Thanks

Answer 1

[Guillaume]

One way:

v = [1,2,3,-1,-2,-3,4,5,6,-7,-6,-3,-5,-4];
transitions = find(diff([0, v<0, 0]));
result = arrayfun(@(s,e) median(v(s:e)), transitions(1:2:end), transitions(2:2:end)-1)

Note that the second negative sequence in your example is [-7,-6,-3,-5,-4] so its median is -5.