Find datapoints a specified distance apart in matrix using while loop

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Emu 2023-3-27

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1935909-find-datapoints-a-specified-distance-apart-in-matrix-using-while-loop

评论： Emu 2023-3-27

t0_pos.mat

I have some data with positive integers (to_pos). I want to find and extract into a second matrix (spacedCrossPoints) datapoints that are a minimum of 30 from each other. So my desired output would be: 1214,2263,2320,8262,8292....

Here is my not working code so far:

gapBetweenCrosses = 30;
for cross = 2:length(t0_pos)-1;
    i = cross;
    if (((t0_pos(cross+1))-(t0_pos(i))) >= gapBetweenCrosses)% && (cross < ((length(t0_pos))-30)); %if gap between row greater than or equal to 30(s)
        spacedCrossPoints(end+1,1) = t0_pos(cross+1); %insert values of crosspoints into matrix
        elseif ((t0_pos(cross+1))) - (t0_pos(i)) < gapBetweenCrosses %&& cross < (length(t0_pos))-30; %if gap is less than 30. skips
        %jump = 30-(((t0_pos(cross+1))) - (t0_pos(cross))); %calculate jump as difference between 30 and different between rows
        while ((t0_pos(cross+1))) - (t0_pos(i)) < gapBetweenCrosses
          cross = cross+1;
          %spacedCrossPoints(end+1,1) = t0_pos(cross+1); %notes new value 30 past last value %NEED TO MAKE CROSS NOT EXCEED length t0_pos
        end
    end
    cross = cross+1;
end
end

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Dyuman Joshi 2023-3-27

"I want to find and extract into a second matrix (spacedCrossPoints) datapoints that are a minimum of 30 from each other."

How does the above statement relate to this - "So my desired output would be: 1214,2263,2320,8262,8292...."

Do you want to obtain all the pair of points whose difference is >= gap?

Emu 2023-3-27

In the attached dataset the datapoints that are 30 or more points from each other are as specified: 1214,2263,2320,8262,8292... They are not pairs.

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Answer 1

Dyuman Joshi 2023-3-27

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1935909-find-datapoints-a-specified-distance-apart-in-matrix-using-while-loop#answer_1201869

编辑：Dyuman Joshi 2023-3-27

在 MATLAB Online 中打开

t0_pos.mat

Points which are >= 30 than the previous point starting with the 1st point -

load t0_pos.mat
gap=30;
k=1;
y=false(size(t0_pos));
y(k)=true;
%loop
while k<numel(t0_pos)
    k=find(t0_pos - t0_pos(k) >= gap, 1);
    y(k)=true;
end
out = t0_pos(y)'
out = 1×34
        1214        2263        2320        8262        8292        8322        8434        8480        9014        9090        9149        9179        9215       14848       14904       15106       15149       15207       15372       15443       16330       16671       16708       20532       20590       20757       20809       23325       23355       23385