MATLAB: No. of elements, mean and standard deviation of a field – conditions on other fields

Question

Hi. I am working with a structure array S (1 X 50,000) with 10 fields.

For example,

Here is the input,

S(1).f1=[10,70,30 40,50,60], S(1).f2=[100,20,50,60,70,140] and S(1).f3=[-10,20,-50,42,-70,140] ;

S(2).f1=[16,98,74,47,99], S(2).f2=[101,54,69,20,11] and S(2).f3=[17,-54,69,-20,37];

S(3).f1=…… , S(3).f2=….. and S(3).f3=………..;

S(4).f1=…. , S(4).f2=….. and S(4).f3=…………;

.

.

S(i).f1=…., S(i).f2=…. and S(i).f3=…………;

Let's say, I have a main condition: 50 < f1 <=100. Based, on this condition I want to calculate few values

I want to know the number of elements in field f1 which satisfy the condition 50 < f1 <=100.

I want to know the number of elements in field f1 whose corresponding f3 > 0.

I want to know the number of elements in field f1 whose corresponding f3 < 0.

I want the mean and sd of f2 elements whose corrseponding f3 > 0.

I want the mean and sd of f2 elements whose corresponding f3 < 0.

Is there a simple way to find the above mentioned parameters?

Answer 1

Maybe something like this?

f1 = [S.f1];
f2 = [S.f2];
f3 = [S.f3];
f1_cond1 = numel(f1(f1 > 50 & f1(f1 <=100)));
f2_idx = f3 > 0;
avg = mean(f2(f2_idx));
sd = std(f2(f2_idx));