How to use the data, but no polar function, to make polar plot?

Hi,

I am wondering how to use the data, but not polar function, to make polar plot in MATLAB.

My data is like between 0to 1/2pi, the value equal to 1;

between 1/2pi to pi, the value equal to 2;

between pi to 3/2pi, the value equal to 3;

between 3/2pi to 2pi, the value equal to 1.5.

I noticed that it is very easy to make polar plot when there is a polar function between theta and r,

however, I only have the data but no function....

I wonder is it possible to make polar plot just using my data? Or...how to make a polar function using my data?

Thanks,

Cece

Answer 1

[Robert]

I would use polar to plot the data; however it looks like R2016a has a preferred option -- polarplot ( doc ).

With polar, you could try

 theta = linspace(0,2*pi,1e3); % more values yeilds a smoother plot
 r = nan(size(theta)); % pre-allocate r
 r(theta<pi/2) = 1;
 r(theta>=pi/2&theta<pi) = 2;
 r(theta>=pi&theta<3*pi/2) = 3;
 r(theta>=3*pi/2) = 1.5;
 r(end) = 1; % makes it a closed loop

 polar(theta,r)

Answer 2

[Thorsten]

theta = deg2rad(0:359); 
r = [1 2 3 1.5]; 
r = repmat(r, 90, 1); r = r(:)';
plot(r.*cos(theta), r.*sin(theta))
axis equal