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Plotting X, Y cordintions with a line short line that indicates the angle

Asked by Ahmed Madhun on 4 Sep 2019
Latest activity Commented on by Ahmed Madhun on 5 Sep 2019
I have a Matrix (M) that looks like this:
X Y Angle
20 30 200
30 100 100
80 450 50
How can i plot a point for each raw as a coordinate? and a short line that indicates the angle/diraction this node is facing.

  2 Comments

What have you tried? Any ideas how to succeed?
Didn't find any tool usful yet. I saw some ideas, where i can use quiver(), but this require a transfrom of the angel to be set as u and v (which i didn't know that they represent)

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2 Answers

Answer by Kelly Kearney
on 4 Sep 2019
 Accepted Answer

With quiver, the u and v arguments represent the horizontal and vertical components of the arrow you want to draw. You can calculate those easily based on the angle:
dat =[...
20 30 200
30 100 100
80 450 50];
u = cosd(dat(:,3));
v = sind(dat(:,3));
plot(dat(:,1), dat(:,2), 'o');
hold on;
s = 0.1; % scaling factor, adjust as desired
quiver(dat(:,1), dat(:,2), u, v, s);
axis equal;

  1 Comment

That's exactly what i was looking for. Thanks!

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Answer by Neuropragmatist on 4 Sep 2019
Edited by Neuropragmatist on 4 Sep 2019

Your question is lacking some detail I suspect. Just to plot the XY data you could do this:
dat =[20 30 200
30 100 100
80 450 50];
figure
plot(dat(:,1),dat(:,2))
But my guess is that you are asking how you can plot lines starting at the XY coordinates with the angles listed in the third column? To do that you will have to choose a length of the lines and then you can do something like this:
% use dat from above
L = 100;
x2 = dat(:,1) + (L .* cosd(dat(:,3))); % use trigonometry to work out position of line 100 units from the starting point
y2 = dat(:,2) + (L .* sind(dat(:,3)));
figure
plot([dat(:,1) x2]',[dat(:,2) y2]')
daspect([1 1 1])
Hope this helps,
M.

  1 Comment

Not really, i have a data set of coordinates (x and y) with represents a node. They also have a third variable which is the angle that i would like to represent, in order to see what this node is facing. i don't need to draw a full line between nodes, just something that can show me the direction of the node

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