polar/plot incompatibility

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Bjorn Gustavsson 2025-10-28，9:05

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https://ww2.mathworks.cn/matlabcentral/answers/2180901-polar-plot-incompatibility

评论： Adam Danz 2025-11-3，15:12

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Can any one explain the design choise that causes this:

polarscatter(linspace(0,pi*2/3,100).^2,...

linspace(0,pi*2/3,100),...

32,...

linspace(0,pi*2/3,100),'filled')

hold on

plot([-1 1],[1 -1],'m')

Error using newplot

Adding Cartesian plot to polaraxes is not supported.

Error in matlab.graphics.internal.newplotwrapper (line 11)

axReturn = newplot(varargin{:});

From my perspective picking polar/cartesian representation of my grid is just that - a choise of either cartesian grid-lines of polar grid-lines. Why should it not be possible to add objects with cartesian coordinates to a region with polar grid-lines or the other way around?

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Cris LaPierre 2025-10-28，12:51

What version of MATLAB are you using?

Bjorn Gustavsson 2025-10-29，9:47

Chris: for this it was 2023a

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回答（1 个）

Star Strider 2025-10-28，13:37

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https://ww2.mathworks.cn/matlabcentral/answers/2180901-polar-plot-incompatibility#answer_1571476

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The original coordinate system predominates, and the subsequent plot call respects that.. You are plotting two points,

and

If you want to plot them as

and

, you need to transform them --

polarscatter(linspace(0,pi*2/3,100).^2,...

linspace(0,pi*2/3,100),...

32,...

linspace(0,pi*2/3,100),'filled')

hold on

% plot([-1 1],[1 -1],'m')

[r,a] = cart2pol([-1 1],[1 -1]) % Transform To Polar Coordinates

r = 1×2

2.3562 -0.7854

a = 1×2

1.4142 1.4142

plot(r,a)

●

figure

plot([-1 1],[1 -1])

axis('equal')

grid

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Bjorn Gustavsson 2025-10-30，20:58

@Walter Roberson "assume".

That still doesn't make it exactly the same as points in a cartesian plane, and that part is something I have to insist makes it fundamentally different, to bend lines to adhere to a map-projection...

Adam Danz 2025-11-3，15:12

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This chat is an interesting read. I want to make sure I understand the idea: @Bjorn Gustavsson is your curiously about why plot(x,y) interprets the arguments as polar values (theta, radius) when plotting to polar axes rather than sticking to a Cartesian interpretation?

I can see that argument.

plot() is like a swiss army knife. It can take datetime, duration, categorical, and various types of numeric data (e.g. geographical, polar, Cartesian). Plot interprets the inputs based on the axis/ruler type. For example, the first line below creates a datetime ruler for the x-axis. The x-values of the 3rd line are therefore interpreted as durations (number of days).

plot(datetime(2000,1,1:5), 1:5, '-bo')

hold on

plot(1:5, 3:7, '-rd')

●

Or, is the question about why Euclidean lines are used to connect points in polar space? I've also wondered this. We recently showed how to get around this in a recent article in the Graphics and App Building blog.

https://blogs.mathworks.com/graphics-and-apps/2025/09/30/polar-plots-with-patches-and-surfaces-r2025a/

I, personally, would like to see an option to connect points in polar space using arch interpolation. I also mentioned this in the following thread:

https://www.mathworks.com/matlabcentral/answers/325599-fill-area-between-two-polar-curves#answer_1567878

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