Keep pairs of corresponding elements in 2 vectors based on conditions

Question

fadams18 2023-3-14

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1928540-keep-pairs-of-corresponding-elements-in-2-vectors-based-on-conditions

编辑： Dyuman Joshi 2023-3-16

I have the problem here: Using this image below: I want to check for several conditions

the orange and green marks are annotations on a signal. If we consider vectors orange, and green which contain the points needed to make the annotations.

The point is to have perfect pairs and ignore all others. i.e. orange(i) and green(i) is a pair if orange(i)<green(i)

so all values in vector orange are lower than their corresponding elements in vector green.

I want to check the following conditions.

I started but some conditions dont work, thats why i need help.

Condition 1: orange must always begin, so if a green begins I delete that green point. [done]

condition 2: if 2 or more greens come before an orange, delete all unecessary green to keep a pair.

condition 3: similarly if several orange exist delete them to keep a pair.

so in the end I want to have a perfect system of pairs, where orange starts a pair. like this:

orange=[212929;213223;213482;213740;214013;214790];
green= [212765;213301;213822;214090;214240;214426;214941];
if green(1)<orange(1)
    green=green(2:end);
end
 lenss =min(length(orange),length(green));
 
 
i = 1;
while i <= lenss
    if abs(green(i)-orange(i)) <0
         green(i) = [];  
         i=1;
        continue;
    else
        i=1+1;  
        continue;
    end
end 

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Jan 2023-3-14

编辑：Jan 2023-3-14

在 MATLAB Online 中打开

abs(green(i)-orange(i)) <0

The output of abs() is >= 0 for all inputs.

The two continue statements have no effect.

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Answer 1

Jan 2023-3-14

2
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1928540-keep-pairs-of-corresponding-elements-in-2-vectors-based-on-conditions#answer_1193015

编辑：Jan 2023-3-14

在 MATLAB Online 中打开

orange = [212929;213223;213482;213740;214013;214790];
green  = [212765;213301;213822;214090;214240;214426;214941];
[x, s]    = sort([orange.', green.']);
index     = strfind(s <= numel(orange), [true, false]);
ok_orange = x(index)
ok_orange = 1×4
      213223      213740      214013      214790
ok_green  = x(index + 1)
ok_green = 1×4
      213301      213822      214090      214941

The idea: sort all elements. If their sorting index is greater than the number of orange elements, they are green. So s <= numel(orange) is a logical vector, which is TRUE for orange and FALSE for green. Now find the neighboring [true, false] pairs.

Kind regards to @Bruno Luong, who told me this method over 20 years ago. :-)