# How to retrieve the location of the points plotted ordered

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Kevin Voogd on 2 Jun 2020
Commented: Star Strider on 2 Jun 2020
I have two vectors x and y which are not sorted. However, when I plot(x,y), it results in the expected plot. Here is an example of the arrays and the plot. As you can see, I would like to have the vectors ordered starting from x(1) = 0, y(1) = 0 and then following the order of the dots as if it was a continuous line. I cannot figure it out how to automatize this process since I have quite a lot arrays/graphs to look at and it is not worth it to do it manually.
x = [1.99802555286103e-05 2.11219844159594e-05 2.28345777469832e-05 2.39763066343323e-05 2.54034677435188e-05 2.59743321871934e-05 2.65451966308679e-05 2.74014932963798e-05 2.85432221837290e-05 2.85432221837290e-05 2.85432221837290e-05 2.85432221837290e-05 2.79723577400544e-05 2.76869255182171e-05 2.65451966308679e-05 2.54034677435188e-05 2.42617388561696e-05 2.28345777469832e-05 2.11219844159594e-05 1.91239588630984e-05 1.71259333102374e-05 1.59842044228882e-05 1.39861788700272e-05 1.19881533171662e-05 9.70469554246784e-06 7.42123776776952e-06 5.70864443674578e-06 3.99605110572207e-06 1.99802555286102e-06 0];
y = [-3.68207566170104e-05 -3.48227310641493e-05 -3.33955699549629e-05 -3.13975444021019e-05 -2.96849510710781e-05 -2.74014932963798e-05 -2.54034677435188e-05 -2.34054421906578e-05 -2.11219844159595e-05 -1.88385266412611e-05 -1.62696366447255e-05 -1.39861788700272e-05 -1.11318566516543e-05 -9.13383109879327e-06 -7.99210221144412e-06 -6.27950888042038e-06 -5.13777999307122e-06 -3.71061888388478e-06 -3.13975444021020e-06 -3.13975444021020e-06 -2.85432221837291e-06 -2.85432221837291e-06 -2.56888999653562e-06 -2.56888999653562e-06 -2.56888999653562e-06 -2.28345777469833e-06 -2.28345777469833e-06 -1.99802555286104e-06 -1.42716110918645e-06 0]; Star Strider on 2 Jun 2020
The easiest way to do that is to use the flip function (or fliplr or flipud, depending on what you want to do).
Try this:
flipx = flip(x);
flipy = flip(y);
figure
plot(flipx, flipy)
grid
figure % Optional
quiver(flipx, flipy, dx,dy) % Optional
grid
The quiver plot just demonstrates that the flip operation does what you want it to do. It is not necesary for the code.

Kevin Voogd on 2 Jun 2020
Dear Star Strider,
indeed the flip function is what I was looking for. You saved me!
Thank you!
Star Strider on 2 Jun 2020
As always, my pleasure!

Fangjun Jiang on 2 Jun 2020
Edited: Fangjun Jiang on 2 Jun 2020
If you run plot(x,y) instead of plot(x,y,'o'), you will see the correct curve. So your data is already "sorted" as you wanted. I would say that you are lucky that the x, y data is in current order. If x is sorted based on its value, it would be hard to get to the current order.
To illustrate the issue
% x data is in the right order, both curve and dot plot are correct
figure;plot(x,y,'o');
figure;plot(x,y);
% x data is sorted by value, curve plot is incorrect
[xx,index]=sort(x);
yy=y(index);
figure;plot(xx,yy,'*');
figure;plot(xx,yy);

#### 1 Comment

Kevin Voogd on 2 Jun 2020
Dear Fangjun Jiang, thank you for your time. However, the answer that Star Strider wrote is what I was looking for. I am sorry if my question was not clear enough.