Limits of polar plots axes

Hello, please see the code atatched that makes a polar plot and adds transparency to it with the included (in the body) function "updateTransparency". The mat file to load is also attached (i.e. 'PolarPlotIssue_v1.mat').

The problem is that if lines 6-8 are commented out (if excluding angles large than 40 degrees), the polar plot becomes very small, i.e. it's not scaled.

How do I make the polar plot as large as the original (when lines 6-8 are NOT commented out)?

THANK YOU!

Answer 1

[Walter Roberson]

You are using polar() which is the older function that uses cartesian axes. It is difficult to customize.

We would normally recommend that you switch to polarplot() but I see that you have hold on and overlay a semi-transparent contourf() which is based on cartesian coordinates.

the = linspace(0,2*pi);
r = the.^2 - cos(the);
h = polar(the,r);

findall(h.Parent)

ans = 
  33×1 graphics array:

  Axes
  Line
  Text     (0)
  Text     (180)
  Text     (330)
  Text     (150)
  Text     (300)
  Text     (120)
  Text     (270)
  Text     (90)
  Text     (240)
  Text     (60)
  Text     (210)
  Text     (30)
  Line
  Line
  Line
  Line
  Line
  Line
  Text     (  40)
  Line
  Text     (  30)
  Line
  Text     (  20)
  Line
  Text     (  10)
  Line
  Patch
  Text
  Text
  Text
  Text

You can see that the older polar() throws up a bunch of text objects for labels, and draws a bunch of line() for the spokes and radii. There are no internal controls for polar() that limit angles.

[alberto tonizzo]

@Walter Roberson do you know how to use contourf() with polarplot()?

Or is there another way to create polar plots in Matlab?

Thanks

[Walter Roberson]

contourf cannot be used with polarplot()

You would have to extract the contour boundaries and convert them to polar coordinates and polarplot those. But angles would very likely go out of range.

It would perhaps be easier to create a second axes in the same position as the first, with axes background color 'none' and possibly using alpha (transparency).

I do not know at the moment whether it is possible to use yyaxis between numeric axes and a polar axes. I would tend to suspect not.