MATLAB: How to plot only half of a polar plot? (i.e. only the lower hemisphere from 90-270)

halfpolar

Hi guys, I require a polar plot to present my data, however I only want to visually plot and represent the lower half of the polar. I wish for it to display only a lower hemisphere semi-circle from 90-270 and not the rest from 0-90 or 270-360.

If anyone knows how I can produce this I would be extremely grateful!

thanks, Mark.

Best Answer

figure
t = 0:.01:2*pi;
polar(t,sin(2*t).*cos(2*t),'--r')
ylim([-0.5 0])

Related Solutions

MATLAB: Can you plot polarplots so that theta zero location is at any arbitrary angle or are top left bottom right the only options

Here's a demo showing how to rotate line objects and theta ticks on polar axes. The orientation of the polar axes is controlled by a uislider within a UIFigure. The slider's callback function updates the "ThetaData" property for all objects on the axes.

Restrictions and notes of caution:

If there are any plotted objects whose angular positions are not controlled by the "ThetaData" property (ie, text objects), this will have to be adapted to work with their positional properties.
Since the ThetaData values are updated for all objects, they will no longer retain their original values. For example, if the original theta value was 0 and it was rotated by 15 deg, then its new theta value will be 15. To get the original theta values back, see the slider's UserData property which stores the current orientation of the polar axes relative to the ThetaZeroLocation.

See inline comments for details.

% Create data for polar plot
th1 = linspace(0,pi*11/6,12); 
r1 = cos(th1);
th2 = linspace(5*pi/6,9*pi/6,20);
r2 = linspace(1,.1,20);
% Create the polar plot
% For this demo, this plot can only contain objects whose 
% angular position is controlled by the 'ThetaData' property. 
fig = uifigure(); 
ax = polaraxes(fig);
hold(ax,'on')
polarplot(ax, th1, r1, 'b-','LineWidth',2);
polarplot(ax, th2, r2, 'ro','MarkerFaceColor', 'r');
polarplot(ax, 0, .9, 'kp', 'MarkerSize', 16, 'MarkerFaceColor', 'y')
titleHandle = title(ax,'Orientation: 0 deg'); 
% Add slider & label
ax.Position([2,4]) = ax.Position([2,4])+[.15,-.15];
uilabel(fig, 'position', [20 60, 400,20], 'Text', 'Adjust orientation of polar axes (deg from ThetaZeroLocation)');
% You can substitute "ValueChangingFcn" and "ValueChangedFcn" for the same callback function.   
sldr = uislider(fig, 'Position', [20, 50, 520, 3], 'Value', 0, 'Limits', [-180,180],...
    'MajorTicks', -180:30:180, 'MinorTicks', [], 'UserData', 0, ... % UserData stores current rotation
    'ValueChangingFcn', @(sldr,event)updatePolarTicks(sldr,event,ax,titleHandle)); 
drawnow(); pause(0.05)
% Define slider's callback function to update the orientation of the polar axes
% relative to the TheatZeroLocation.
function updatePolarTicks(sldr,event,ax,titleHandle)
    % Update title and compute rotation amount; store new orientation in memory. 
    titleHandle.String = sprintf('Orientation: %.0f deg', event.Value); 
    rotation = event.Value - sldr.UserData; %(+=CCW, -=CW)
    sldr.UserData = event.Value;
    
    % Convert rotation angle to radians, wrapped to [0,2pi]
    dwrap = @(d)mod(d,360) + (d>0 & mod(d,360)==0).*360; %wrap degrees to 0:360
    deg = dwrap(rotation); 
    rad = pi/180*deg; 
    
    % Rotate line objects
    chil = ax.Children;
    thData = get(chil, 'ThetaData'); 
    thDataRot = cellfun(@(c){c+rad},thData); 
    set(chil, {'ThetaData'}, thDataRot)
    
    % Update ticks
    origTickLabs = ax.ThetaTickLabel;
    [newTicks, tickLabIdx] = unique(dwrap(unique(mod(ax.ThetaTick,360),'stable') + deg));
    ax.ThetaTick = newTicks; 
    ax.ThetaTickLabel = origTickLabs(tickLabIdx);
end

MATLAB: How to plot polar plot from -pi to pi instead of 0 to 2*pi

What error do you get?

I tried the below and I don't get any error.

theta = linspace(-pi,pi,25);
rho = 2*theta;
p = polarplot(theta,rho);
thetalim([-180 180])

Best Answer

Related Solutions

MATLAB: Can you plot polarplots so that theta zero location is at any arbitrary angle or are top left bottom right the only options

MATLAB: How to plot polar plot from -pi to pi instead of 0 to 2*pi

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