Formatting data using an if function

Question

Benedikt Wessel 2018-9-21

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/420188-formatting-data-using-an-if-function

评论： Benedikt Wessel 2018-9-22

Hello everybody, how can I adjust the data, so that the purple curve will always be connected? The next purple section should start at the end of the section before.... I've no clue how to do that. I really need help, because of this thing I'm not able to finish my bachelor thesis. Thanks guys.

(Ignore the legend)

C=cumsum(diffE,'omitnan'); % needed Capacity 
Cbmax= 1000; % in MWH, max. capacity of the battery storage
Cbmin= 100; % in MWh, deep charge border 
imax= C>=Cbmax-Cbmin; % find where C is larger than the Capacity
imin= C<=0; % find where C is =0
C(imax) = Cbmax-Cbmin; % if C is larger than Cbmax: C=Cbmax
C(imin) = Cbmin-Cbmin; % if C is smaller than Cbmin: C=Cbmin 
Cres=cumsum(diffE,'omitnan');
for k=1:length(Cres)-1
    if Cres(k)>(Cbmax-Cbmin) && Cres(k)>Cres(k+1) 
           C(k+1)=C(k)-Cres(k)+Cres(k+1); 
    end
    if Cres(k)>(Cbmax-Cbmin) && C(k)<(Cbmax-Cbmin)
         C(k+1)=C(k)-Cres(k)+Cres(k+1); 
    end
end

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Answer 1

Stephen23 2018-9-21

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https://ww2.mathworks.cn/matlabcentral/answers/420188-formatting-data-using-an-if-function#answer_337823

编辑：Stephen23 2018-9-22

在 MATLAB Online 中打开

"how can I adjust the data, so that the purple curve will always be connected?"

loop over the length of the data vector.
detect any discontinuities (e.g. difference/offset, or some other metric).
shift the remaining data by the detected offset (use indexing).

Something like this:

for k = 2:numel(vec)
    d = diff(vec(k-1:k))
    if abs(d)>tol  % pick a tolerance, or some metric
        vec(k:end) = vec(k:end)-d;
    end
end

I just tried this on a fake data vector:

tol = 2;
vec = [0,1,2,3,4,10,11,12,13];

giving:

>> vec
vec =
   0   1   2   3   4   4   5   6   7

You could fine-tune the algorithm so that it includes an offset of the same sign as d, but with magnitude tol. Also it would pay to do some reading into detecting discontinuities:

https://www.mathworks.com/help/wavelet/examples/detecting-discontinuities-and-breakdown-points.html

https://en.wikipedia.org/wiki/Step_detection

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Stephen23 2018-9-22

编辑：Stephen23 2018-9-22

在 MATLAB Online 中打开

"But unfortunately the diff functions is always in an endless loop"

Check if you have any other functions named diff:

which diff -all

And if so, rename them. Also ensure that you do not have any variables name diff. Note that diff is not strictly required, you could do this:

d = vec(k)-vec(k-1)

Benedikt Wessel 2018-9-22

在 MATLAB Online 中打开

Cres.mat

Oh nice, now it's working. I although tried to use indexing to find the gaps and to adjust them, but my code is a mess I think. Sorry to bother you, but can you find my mistakes? I also added the needed data if it's helpful. Here's my code:

C=cumsum(diffE,'omitnan'); % needed Capacity, will be adjusted by Cbmax anc Cbmin
Cres=C;
Cbmax= 1000; % in MWH, max. capacity of the battery storage
Cbmin= 100; % in MWh, deep charge border 
imax= C>=Cbmax-Cbmin; % find where C is larger than the Capacity
imin= C<=0; % find where C is =0
C(imax) = Cbmax-Cbmin; % if C is larger than Cbmax: C=Cbmax
C(imin) = Cbmin-Cbmin; % if C is smaller than Cbmin: C=Cbmin
Cres=cumsum(diffE,'omitnan');
change=zeros(length(diffE),1);
for k=1:length(Cres)-1
    if Cres(k)>(Cbmax-Cbmin) && Cres(k)>Cres(k+1) 
           C(k+1)=C(k)-Cres(k)+Cres(k+1); 
    end
    if Cres(k)>(Cbmax-Cbmin) && C(k)<(Cbmax-Cbmin)
         C(k+1)=C(k)-Cres(k)+Cres(k+1); 
    end
      change(k)= Cres(k)>(Cbmax-Cbmin) && Cres(k+1)<(Cbmax-Cbmin);
end
cha=find(change==1); % find the positions of the gaps between the sections
for k = 1:length(C)-1
   for n=cha
       if C(k)==C(n)  % find the data with the "crack"
            C(k:n+1) = C(k:n+1)-C(n)-C(n-1); % subtract every value in the actual section with the difference between the sections
       end
   end
end