In R2016a and later releases, after having created a polar axes (via the "polaraxes" function directly or as a result of creating a polar plot via the "polarplot" function), you can get the "RAxis" property of that polar axes. The "RAxis" object has a property named "Label" that contains a "Text" object, which has a property named "String". For details about the "RAxis" property, refer to the following link:
To modify the r-axis label, you can adapt the following example code:
ax = polaraxes;
ax.RAxis.Label.String = 'My Label';
The "RAxis" property is a Numeric Ruler. To further manipulate the r-axis, you can modify the Numeric Ruler Properties of "ax.RAxis". For details, refer to the following link:
