How to skip vectors and plot the n-vector with quiver ( 2D-vecor-vector field)

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Emerson De Souza
Emerson De Souza 2011-10-19
回答： ali veli 2019-3-6
I want to know how to skip some rows by plotting a two-dimensional vector-field.
For example, let U and V be the coordinates and x and y the vector components as writen below:
U=[1 2 3 4 5 6 7 8 9 10];
V=[0 0 0 0 0 0 0 0 0 0];
x=[0 0 0 0 -1 1 0 2 1 2];
y=[1 2 -1 -2 0 0 0 0 1 2];
then I use quiver to plot the vector-field as follows:
Vector=[U' V' x' y'];
quiver(Vector(:,1),Vector(:,2),Vector(:,3),Vector(:,4),0,'LineWidth',2,'MaxHeadSize',.1); axis([0 12 -3 3])
Now it would be great if someone could tell me what I need to write to plot only every second, third or n-vector (row)
I thank you in advancoe for your help
Emerson

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采纳的回答

the cyclist
the cyclist 2011-10-19
Put these two lines in before the quiver() command:
plotEveryThisMany = 2;
Vector = Vector(1:plotEveryThisMany:end,:)
This will index into "Vector" at every other element. This can be generalized to choose whatever elements you want to plot.
  2 个评论
Emerson De Souza
Emerson De Souza 2011-10-19
Thank you,
it has been a great suggestion. It fixed my problem!!!
Do you also know how to skip data by plotting 2d-curves?
I frequent have to do with this issue and don't know how.
For example, let:
x = 0:pi/100:2*pi;
y = sin(x);
plot(x,y);
What should I write if I want to display only every n-ten data point?
Thank you in advance
Emerson
the cyclist
the cyclist 2011-10-20
You could do it like this:
xToPlot = x(1:10:end);
yToPlot = y(1:10:end);
plot(xToPlot,yToPlot)

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更多回答（2 个）

Sachini Pathirana
Sachini Pathirana 2019-2-14
编辑：Sachini Pathirana 2019-2-14
How can I use the same thing to select points in a 2D matrix? I have a mtrix of 695*1028 and i want to plot selected points using quiver.
ali veli
ali veli 2019-3-6
Hi. How do I get this vector graphic with quiver3grafik.png

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