# Iterations on field conditions of a structure array

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SS 2019년 10월 7일
댓글: Piyush Dubey 2019년 11월 11일
Hi. I am working with a structure array S (1 X 50,000) with 10 fields. I want to find few paramters based on few conditions. Is there a simple way to do such iterations shown below using a loop and save them in a structure?
f1 = [S.f1];
f2 = [S.f2];
f3 = [S.f3];
%% ITERATION 1:
idx1 = f1 > 0 & f1 <=10;
% Parameter 1
num1 = numel(f1(idx1));
avg1 = mean(f2(idx));
sd1 = std(f2(idx));
% Parameter 2
idx2 = f3 > 0;
idx = idx1 & idx2;
pos_num1 = numel(f1(idx));
pos_avg1 = mean(f2(idx));
pos_sd1 = std(f2(idx));
% Parameter 3
idx2 = f3 < 0;
idx = idx1 & idx2;
neg_num1 = numel(f1(idx));
neg_avg1 = mean(f2(idx));
neg_sd1 = std(f2(idx));
%% ITERATION 2:
idx1 = f1 > 10 & f1 <=20;
% Parameter 1
num2 = numel(f1(idx1));
avg2 = mean(f2(idx));
sd2 = std(f2(idx));
% Parameter 2
idx2 = f3 > 0;
idx = idx1 & idx2;
pos_num2 = numel(f1(idx));
pos_avg2 = mean(f2(idx));
pos_sd2 = std(f2(idx));
% Parameter 3
idx2 = f3 < 0;
idx = idx1 & idx2;
neg_num2 = numel(f1(idx));
neg_avg2 = mean(f2(idx));
neg_sd2 = std(f2(idx));
% so on till 20 interations.
The result should be saved like:
Result.num=[num1,num2,num3.........,num20];
Result.pos_num=[pos_num1,pos_num2,pos_num3,.....,pos_num20];
Result.neg_num=[neg_num1,neg_num2,neg_num2,......,neg_num20];
Result.avg=[avg1,avg2,avg3,.....avg20];
.. so on.
Any help will be highly appreciated.

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### 채택된 답변

Piyush Dubey 2019년 10월 10일
Hi,
It is not very clear from your explanation what you are trying to accomplish. If you are trying to iterate using indices that satisfy some conditions, you should make a matrix with each column containing indices of vector 'f1' that satisfy the required conditions. For example,
idx_list = [(f1 > 0 & f1 <= 10) (f1 > 10 & f1 <= 20) (f1 > 20 & f1 <= 30)];
idx_list_size = 3;
num_list = zeros(idx_list_size, 1);
And iterate in the following way:
for i=1:idx_list_size
num_list(i) = numel(f1(idx_list(:, i)));
end
##### 댓글 수: 2표시숨기기 이전 댓글 수: 1
Piyush Dubey 2019년 11월 11일
You can save a list to a structure as follows:
Result.num_list = num_list;

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