MATLAB: How to label the R-axis in a polar plot

MATLAB

How do I label the R-axis in a polar plot?

Best Answer

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:

www.mathworks.com/help/releases/R2016b/matlab/ref/polaraxes-properties.html#property_RAxis

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:

https://www.mathworks.com/help/releases/R2016b/matlab/ref/numericruler-properties.html

Related Solutions

MATLAB: Set the Location of R-axis Labels using ‘polar’ in MATLAB R2016a

Moving the R-axis with 'polarplot' The 'polarplot' function was introduced in MATLAB R2016a as a replacement for the 'polar' function, which makes it easier to customize polar plots.

See the documentation linked below, which outlines the properties of 'polaraxes' for more information:

https://www.mathworks.com/help/releases/R2016a/matlab/ref/polaraxes-properties.html

The 'RAxisLocation' property can be used to set the location of the R-axis labels in degrees:

% Create a polar plot.
pp = polarplot(sin(0:0.01:10*pi));
% Get a handle to the polar plot axes.
ax = gca;
% Set the location of the R-axis labels in degrees.
degrees = 300;
ax.RAxisLocation = degrees;

If you are unable to use the 'polarplot' function, you can follow the workarounds below to hide or move the R-axis labels using the 'polar' function.

Hiding the R-axis with 'polar' 1.) To hide the R-axis labels, first locate all of the 'Text' objects in the graphics object hierarchy using the 'findall' command. Then, filter the results using the 'HorizontalAlignment' property of the 'Text' objects.

PLEASE NOTE: This filtering method relies on the default value being set to 'left' for the 'HorizontalAlignment' property of the 'Text' objects created by the 'polar' command.

% Taken from 'doc polar' example:

% http://www.mathworks.com/help/matlab/ref/polar.html

theta = 0:0.01:2*pi;
rho = sin(2*theta).*cos(2*theta);
f = figure;
polar(theta,rho,'--r');
% Extract all of the 'Text' objects from the polar plot.

ax = findall(f.Children, 'Type', 'Axes');
% Filter the 'Text' objects by the 'HorizontalAlignment' property.

% PLEASE NOTE: This may not generalize to other versions of MATLAB

% where the default 'HorizontalAlignment' value for R-axis labels is not

% set to 'left'.

labels = findall(ax, 'Type', 'Text', 'HorizontalAlignment', 'left');
% Hide all the R-axis labels.
[labels.Visible] = deal('off');

Moving the R-Axis with 'polar' 2.) To move the R-axis labels, first locate the corresponding 'Text' objects in the graphics object hierarchy, as described above. Then, iterate over the appropriate set of 'Text' objects, and update the 'Position' property of each object.

The code below provides a simple method of setting the 'Position' property of each 'Text' object in degrees on the polar plot. You can modify the value of the 'degrees' variable to choose where you want to place the R-axis labels on the polar plot.

% Taken from 'doc polar' example:
% http://www.mathworks.com/help/matlab/ref/polar.html
theta = 0:0.01:2*pi;
rho = sin(2*theta).*cos(2*theta);
f = figure;
polar(theta,rho,'--r');
% Extract all of the 'Text' objects from the polar plot.
ax = findall(f.Children, 'Type', 'Axes');
% Filter the 'Text' objects by the 'HorizontalAlignment' property.
% PLEASE NOTE: This may not generalize to other versions of MATLAB
% where the default 'HorizontalAlignment' value for R-axis labels is not
% set to 'left'.
labels = findall(ax, 'Type', 'Text', 'HorizontalAlignment', 'left');
% Set the degrees of the R-axis Labels.
degrees = 300;
% Update the position of each R-axis label.
for label = labels'
    currentX = label.Position(1);
    currentY = label.Position(2);
    radius = sqrt(currentX^2 + currentY^2);
    newX = cos(degtorad(degrees)) * radius;
    newY = sin(degtorad(degrees)) * radius;
    label.Position = [newX, newY];
end

MATLAB: Is there a way to move the r-axis tic labels in a polar plot to another theta angle

Use the polaraxes property RAxisLocation.

t = 0 : .01 : 2*pi;
h = polarplot(t, sin(2*t).*cos(2*t), '--r');
ax = ancestor(h, 'polaraxes');
ax.RAxisLocation = 180;

Best Answer

Related Solutions

MATLAB: Set the Location of R-axis Labels using ‘polar’ in MATLAB R2016a

MATLAB: Is there a way to move the r-axis tic labels in a polar plot to another theta angle

Related Question