Length of the structure array

Question

SS 2020-6-9

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/544985-length-of-the-structure-array

评论： SS 2020-6-10

Hi. I am working with a structure array S (1 X 20,000) with 3 fields. I want to count the number of S(i) that meet a condition on one of its fields. For example,

Here is the input,

S(1).f1=[11,17,3,18,15,13], S(1).f2=[100,20,50,60,70,140] and S(1).f3=[-10,20,-50,42,-70,140] ;
S(2).f1=[10,12,14,17,19], S(2).f2=[101,54,69,20,11] and S(2).f3=[17,-54,69,-20,37];
S(3).f1=S(1).f1=[19,17,13,14,15,10,11,16], S(3).f2=..... and S(3).f3=...........;
S(4).f1=[11,17,30,108,15,13,37,14], , S(4).f2=..... and S(4).f3=............;
.
.
S(i).f1=...., S(i).f2=.... and S(i).f3=............;

Let's say, I have a condition on f1: 10 < f1 <=20. Based, on this condition I want the count of S(i) whose f1 is strictly in the these limits. In this example, S(2).f1 and S(3).f1 has all the f1 in bewteen 10 and 20, the count is 2.

I want to implement this on S (1 X 20,000). Can someone help me with this?

Thanks, in advance.

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Answer 1

Walter Roberson 2020-6-10

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https://ww2.mathworks.cn/matlabcentral/answers/544985-length-of-the-structure-array#answer_449057

在 MATLAB Online 中打开

count = nnz(arrayfun(@(S) all(10 < S.f1 & S.f1 <= 20), S))

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Walter Roberson 2020-6-10

在 MATLAB Online 中打开

mask = arrayfun(@(s) all(10 < s.f1 & s.f1 <= 20), S);
count = nnz(mask);
selected_f1_element_counts = cellfun(@numel, {S(mask).f1});
selected_f2 = {S(mask).f2};
selected_f2_means = cellfun(@mean, selected_f2);
selected_f2_variances = cellfun(@var, selected_f2);