Connecting final and initial point in simple x-y plot (Plotting closed curve/polygon)

Question

Say, for example, I had ...

x = [1 1 2 2];
y = [1 2 2 1];
plot(x, y, \'b-\');

I will get a plot with lines connecting the points (1,1), (1,

Answer 1

Do you have the Image Processing Toolbox? If yes,

 impoly(hparent, position, 'Closed')

might be of use to you.

http://www.mathworks.de/help/toolbox/images/ref/impoly.html

Answer 2

impoly can be useful, however, it creates a modifiable curve which is slower than plot.

You can write a simple function for that:

function plotc(x,y,varargin)  
    x = [x(:) ; x(1)];   
    y = [y(:) ; y(1)];  
    plot(x,y,varargin{:})  
end

By the way, the (:) colon operator is used as defensive programming means. In this way, x and y can be either row or column vectors.

The varargin allows using additional parameters, like:

 plotc(x,y,'Color','r');
 plotc(x,y,'Parent',a,'LineWidth',2);

Answer 3

Unless your final and last points are the same then plot won't know that you want a closed curve. So either add an additional point to your list to plot or try using, for example, rectangle.