I want to know the method for removing excessive angle data.

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재혁 2024-2-29

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回答： Mathieu NOE 2024-2-29

I want to remove data, if current direction larger or smaller about mean current direction +15, - 15(degree), respectively.

First figre, I can remove data by up and down line(mean current direction +15 or -15)

But case of Figure2, some datas exceed 360(degree), So I don't how to remove unneedful data....

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재혁 2024-2-29

编辑：Walter Roberson 2024-2-29

在 MATLAB Online 中打开

for i = 1:2:(length(SoundSpeed)-2)
    U_vec2(i,:) = nanmean([U_vec(i,:) ;U_vec(i+1,:)],1); % 5분간격으로 되어있지만 10분간격으로 만들기 위해 2간격으로 평균을 하였음
    V_vec2(i,:) = nanmean([V_vec(i,:) ;V_vec(i+1,:)],1);
end
U_vec2(find(U_vec2(:,1) == 0),:) = []; V_vec2(find(V_vec2(:,1) == 0),:) = [];
Current_dir = (atan2(-U_vec2(:,1:19),-V_vec2(:,1:19)) + pi)*180/pi;
Magvel2 = sqrt(U_vec2.^2+V_vec2.^2); % magniture^2 = U^2 + V^2
mean_Current_dir = nanmean(Current_dir,2);
%%
for i = 1:length(Current_dir)
    indind{i} = find(Current_dir(i,:) > mean_Current_dir(i) + 15 | Current_dir(i,:) < mean_Current_dir(i) - 15);
end
for i = 1:50:length(Current_dir)
    figure(i);
    scatter(log(Depth(1:19)),Current_dir(i,:)); hold on
    yline(mean_Current_dir(46));
    yline(mean_Current_dir(46)+15);
    yline(mean_Current_dir(46)-15);
    ylabel('Current direction (^o)','fontname','arial','fontweight','bold','fontsize',20);
    xlabel('Depth (mab)','fontname','arial','fontweight','bold','fontsize',20);
end

here to my code,

and my current direction data is degree(0 ~ 360), so if mean current direction is 340 then, my code can not identify 0 ~ 10

My data length is approximately 3000

Mann Baidi 2024-2-29

在 MATLAB Online 中打开

for i = 1:length(Current_dir)
    indind{i} = find(Current_dir(i,:) > mean_Current_dir(i) + 15 | Current_dir(i,:) < mean_Current_dir(i) - 15);
end

What is the significance of 'indind' variable?

재혁 2024-2-29

This is a variable used to identify values that exceed or fall short of 15 degrees from the mean flow direction.

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Answer 1

Mathieu NOE 2024-2-29

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2088421-i-want-to-know-the-method-for-removing-excessive-angle-data#answer_1418811

在 MATLAB Online 中打开

hello @재혁

IMO , there is no need to use a for loop to compute 'indind' variable

also nanmean is obsolete, you can use mean with 'omitnan' option instead.

here a very simplified code to show how to remove (replace) values exceeding your limits with NaN's

Current_dir = 45*rand(100,1); % random numbers between 0 and 45

% mean_Current_dir = nanmean(Current_dir,2); obsolete

mean_Current_dir = mean(Current_dir,'omitnan');

%% No need for a for loop here

% for i = 1:length(Current_dir)

% indind{i} = find(Current_dir(i,:) > mean_Current_dir(i) + 15 | Current_dir(i,:) < mean_Current_dir(i) - 15);

% end

indind = (Current_dir > mean_Current_dir + 15) | (Current_dir < mean_Current_dir - 15);

% create data and remove values above and below threshold

Current_dir_cor = Current_dir;

Current_dir_cor(indind) = NaN;

scatter(1:numel(Current_dir),Current_dir); hold on

scatter(1:numel(Current_dir),Current_dir_cor,'*');

yline(mean_Current_dir);

yline(mean_Current_dir+15);

yline(mean_Current_dir-15);

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