How to: Merging multiple graph lines

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Patrick
Patrick on 18 Oct 2014
Edited: vi trung kien on 21 Mar 2018
Hello Guys,
my problem is that I have several data sets of different x-Arrays and always the same y-Array. Basically my plot functions looks like this: plot(x1,y,'g',x2,y,'b'....)
As I have drawn in the picture I want to merge all the lines as to always keep the lowest y-values going from left to right in terms of x-values. This should creat one single new plot that looks like the black line in the right picture. The left picture demonstrates the overlapping data sets.
Can I solve this problem graphically, e.g. using a plotting function to always display the lowest y-value or do I need to create a new 2D array that always picks the lowest y-value for every x- value? Maybe you can give me a base to start from. Sorry about my "untechnical" explanation, Im new to Matlab and coding in general.
Thanks in advance for your support. Pat
  2 Comments
Guillaume
Guillaume on 18 Oct 2014
It looks like you meant to attach or (better) embed a figure, but seems like you forgot
Patrick
Patrick on 20 Oct 2014
Thanks Guillaume,
just attached the image.
Regards Pat

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Accepted Answer

Guillaume
Guillaume on 20 Oct 2014
Edited: Guillaume on 20 Oct 2014
I would concatenate all your x, get the unique values and their position and use the position with accumarray to get the minimum of y:
xall = [x1 x2 x3 ...];
[x, ~, indices] = unique(xall);
y = accumarray(indices, repmat(y, 1, N)', [], @min); %where N is the number of xi
plot(x, y);
edited for missing comma
  10 Comments
Patrick
Patrick on 26 Oct 2014
Thanks for your reply, I will see what the results might be, but I get your point with the noise. That's the reason I was looking for a graphical approach to my problem in the first place. Do you know of any other mehtod tol realize what I pointed out in the attached image?
Patrick
Patrick on 27 Oct 2014
Okay, I put the resulting diagram into the attachment. For my purpose the occurring noise is not really significant. Thanks a lot for your help, Guillaume!

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More Answers (1)

Rick Rosson
Rick Rosson on 18 Oct 2014
x = [ x1 x2 x3 ... ];
N = length(x)/length(y);
y = repmat(y,1,N);
plot(x,y);
  2 Comments
Patrick
Patrick on 20 Oct 2014
Hello Rick,
thanks for your answer! It gives me the same results as my previous code though:
figure(1) plot(n1,bcr,'b',n2,bcr,'r',n3,bcr,'y',n4,bcr,'m',n5,bcr,'m',n6,bcr,'g',n7,bcr,'k',n8,bcr,'b',n9,bcr,'r',n10,bcr,'y')
VS:
figure(2) n = [n1 n2 n3 n4 n5 n6 n7 n8 n9 n10]; N = length(n)/length(bcr); bcr = repmat(bcr,1,N); plot(n,bcr)
However, I dont want 10 individual graph lines in one diagram. What I need is one single united line that always displays Ymin(n), like I have scatched in the pictures attached.
Oops, sorry about that attachment. Forgot to hit the "Attach file" button.
vi trung kien
vi trung kien on 21 Mar 2018
Edited: vi trung kien on 21 Mar 2018
Dear Patrick, Can you suggest for me how to get one single united line that always displays Ymin(n), like you have scratched in the pictures attached.My problem the same as you before. Thanks for your help.

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