MATLAB: How to find mean of a vector including only a specific range of elements

Question

I am new with matlab, in advance sorry for my question. How can I find the mean of a vector that only takes elements between 15 and 25.

Ex.

I have a vector: v = [20 8 15 19 7 31]

What i want as output for this vector is (20+15+19)/3 = 18.

I know that the equation to use is:

sum(v)/length(v) = mean(v)

but i only want to include elements from 15:25 in any(!) vector.

My question: How can l write a program that computes and returns the mean, taking only the valid measurement (15-25)? This is regarding both vectorization and/loops

So far i have this code:

 function averageRate = fermentationRate(vector)
averageRate = 0;
for k = 1:length(vector)
    if (vector(k) < 25 && vector(k) > 15)
        averageRate = (averageRate + vector(k));
    end
end

That only tells the sum of the vector, i miss the dividing by length(vector). How can l add this?

Answer 1

vector = whatever;
min_value = whatever; % 15 in your example
max_value = whatever; % 25 in your example
x = vector >= min_value & vector <= max_value; % or > and < instead of >= and <=
result = mean(vector(x));