plotting circles

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Yasmin Tamimi
Yasmin Tamimi on 12 Mar 2011
Commented: Michelle Hirsch on 11 Dec 2023
How can I plot circles, same radius and different centers, all in one graph. I used the following command to draw +,o,diamond: plot (x,y,'ro',u,v,'gd',A,B,'b+'); where x,y,u,v,A,B are all row vectors. And I want to add circles to that plot where the o will be the center.
  1 Comment
fatima ibrahim
fatima ibrahim on 29 Feb 2020
function draw_circle1(x,y,R,c)
t =0:0.05:6.28;
x1 = (x +R*cos(t))';
y1= (x +R*sin(t))';

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Accepted Answer

Paulo Silva
Paulo Silva on 12 Mar 2011
Here's a function to draw circles:
function circle(x,y,r)
%x and y are the coordinates of the center of the circle
%r is the radius of the circle
%0.01 is the angle step, bigger values will draw the circle faster but
%you might notice imperfections (not very smooth)
ang=0:0.01:2*pi;
xp=r*cos(ang);
yp=r*sin(ang);
plot(x+xp,y+yp);
end
If you want to add circles you must insert the command
hold on
before the circles being added.
  8 Comments
Rik
Rik on 3 May 2020
It's the step size. You can use the colon in two ways when you create an array:
start:stop
start:step:stop
Özgür Saglam
Özgür Saglam on 3 May 2020
Thank you very much!

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More Answers (3)

Michelle Hirsch
Michelle Hirsch on 29 Jan 2016
It's counter-intuitive, but this is actually really easy with the rectangle function. From the rectangle documentation :
pos = [2 4 2 2];
rectangle('Position',pos,'Curvature',[1 1])
axis equal
  5 Comments
Royi Avital
Royi Avital on 10 Dec 2023
@Michelle Hirsch, It would be great if it had the DisplayName property like most other objects.
It makes easier when adding it to the legend.
Michelle Hirsch
Michelle Hirsch on 11 Dec 2023
@Royi Avital I think it's more than just adding DisplayName - annotations like rectangle (intentionally) don't show up in legend since they are meant to be annotations, not data. Are you interested in being able to include annotations in legend? If so, please share more about your use case so I make sure we understand what you are thinking.

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Chad Greene
Chad Greene on 21 Aug 2014
This'll do the job.

Image Analyst
Image Analyst on 20 Jan 2016
Edited: Image Analyst on 15 Apr 2022
numCircles = 15;
x = 5 + randi(95, numCircles, 1);
y = 5 + randi(95, numCircles, 1);
radius = 2 * ones(numCircles, 1);
viscircles([x, y], radius);
grid on;
axis equal

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