How to find mean of a vector including only a specific range of elements
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Sandie Nhatien Vu
on 5 Aug 2016
Edited: Sandie Nhatien Vu
on 6 Aug 2016
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?
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Accepted Answer
James Tursa
on 6 Aug 2016
Edited: James Tursa
on 6 Aug 2016
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));
3 Comments
Stephen23
on 6 Aug 2016
function out = fermentationRate(vec,lwr,upr)
out = mean(vec(lwr<vec & vec<upr));
end
and calling it:
>> fermentationRate([20.1, 19.3, 1.1, 18.2, 19.7, 121.1, 20.3, 20.0], 15, 25)
ans =
19.6
More Answers (1)
Star Strider
on 6 Aug 2016
This works:
v = [20 8 15 19 7 31]; % Vector
UL = 25; % Upper Limit
LL = 15; % Lower Limit
v_mean = sum(v((v >= LL) & (v <= UL))) ./ sum(((v >= LL) & (v <= UL))) % Mean Of ‘v’ Given Constraints
vm =
18
It is necessary to use ‘>=’ and ‘<=’ to get the result you want.
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