How can I split measured data in separate vectors, depending on sign value?

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Anna B. 2022-3-7

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https://ww2.mathworks.cn/matlabcentral/answers/1665444-how-can-i-split-measured-data-in-separate-vectors-depending-on-sign-value

评论： Star Strider 2022-3-7

Hello! Is it possible to split measured data f.e.v= [1 2 3 4 5 4 3 2 1 2 3 4 5 4 3 2 1] in separate vectors, f.e. only the 'growing' values: v1=[1 2 3 4 5], v2=[1 2 3 4 5].

Maybe with a find(sign(diff(v))==1) ?

Thank you!

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Answer 1

Star Strider 2022-3-7

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https://ww2.mathworks.cn/matlabcentral/answers/1665444-how-can-i-split-measured-data-in-separate-vectors-depending-on-sign-value#answer_911799

在 MATLAB Online 中打开

One approach —

v= [1 2 3 4 5 4 3 2 1 2 3 4 5 4 3 2 1];
dv = gradient(v);
sel = v(dv>=0);
dsel = diff([1 find(diff([sel(1) sel])<0) numel(sel)+1]);
C = mat2cell(sel, size(sel,1), dsel)
C = 1×2 cell array
    {[1 2 3 4 5]}    {[1 2 3 4 5]}
v1 = C{1}
v1 = 1×5
     1     2     3     4     5
v2 = C{2}
v2 = 1×5
     1     2     3     4     5

.

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Anna B. 2022-3-7

编辑：Anna B. 2022-3-7

Thank you very much for the quiсk response. I have tried both variants and it works perfectly!

Star Strider 2022-3-7

As always, my pleasure!

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Answer 2

Jan 2022-3-7

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https://ww2.mathworks.cn/matlabcentral/answers/1665444-how-can-i-split-measured-data-in-separate-vectors-depending-on-sign-value#answer_911779

编辑：Jan 2022-3-7

在 MATLAB Online 中打开

Start with a simple loop approach:

v  = [1 2 3 4 5 4 3 2 1 2 3 4 5 4 3 2 1];
dv  = [false, diff(v) > 0, false];
ini = strfind(dv, [false, true]);
fin = strfind(dv, [true, false]);
C   = cell(1, numel(ini));
for iC = 1:numel(ini)
   C{iC} = v(ini(iC):fin(iC));
end
C
C = 1×2 cell array
    {[1 2 3 4 5]}    {[1 2 3 4 5]}