Log scale for radius axis in a polar plot

Question

btåla 2019-1-31

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/442489-log-scale-for-radius-axis-in-a-polar-plot

回答： Mike D. 2020-11-25

Hi everyone,

I am looking for a 'trick' to make a polar plot (polarscatter in this case) which presents my data on a log scale through the r-axis.

Has anyone been able to do that. It seems like it is not possible with 'traditional' ways like setting the RLim. The point is that I have many data that are in between 10e-6 and 10e-2. All I get is a plot with a bunch of data overlapping around 0 and some scattered data around 10e-2. I would like to have a plot where on the r-axis I have a range that goes from 10e-6 to 10e-2, as only in this way I can clearly visuallize the data close to 10e-6.

I know that since it is a polar plot, the r range starts from 0 and the log of it is infinite but surprisingly, I see very similar plots done with matlibplot in python or other softwares (licensed ones) but I would like to make use of Matlab if that is possible.

Any help is appreciated

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Star Strider 2019-1-31

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/442489-log-scale-for-radius-axis-in-a-polar-plot#answer_358925

在 MATLAB Online 中打开

Try this:

th = linspace(0, 2*pi, 9);                                          % Create Angles
r = rand(1, numel(th)) .* 10.^(1:numel(th))-9;                      % Create Data
figure
polarplot(th, log10(r), 'p')
Ax = gca;
Ax.RTick = (2:2:numel(th)-1);
Ax.RTickLabel = compose('10^{%2d}',(2:2:numel(th)-1)-10);
% Ax.RTickLabel = sprintfc('10^{%2d}',(2:2:numel(th)-1)-10);          % Use ‘sprintfc’ If You Do Not Have ‘compose’

Experiment to get the result you want.

4 个评论
显示 2更早的评论隐藏 2更早的评论

btåla 2019-2-3

Thank you Star,

following your suggestions I was able to plot the way I wanted. I just needed to fix the theta and r ticks and labels.

Thanks again,

Star Strider 2019-2-3

As always, my pleasure!

请先登录，再进行评论。

Answer 2

Mike D. 2020-11-25

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/442489-log-scale-for-radius-axis-in-a-polar-plot#answer_556148

在 MATLAB Online 中打开

polarPlotLog.JPG

Here is how I created a logarithmic RAxis for altitudes:

            hAx2 = polaraxes(hFig,'OuterPosition',AxOutPos2,'ThetaAxisUnits','degrees', ...
                'ThetaDir','clockwise','ThetaZeroLocation','top','FontSize',10', ...
                'ThetaTick',0:30:360,'Color',[0 0 0],'ThetaColor',[1 1 1], ...
                'ThetaTickLabel', {'N','','','E','','','S','','','W','',''}, ...
                'RAxisLocation',15,'RLim',[1 5.301],'RTick',[3,4,5],'RColor',[1 1 1], ...
                'RTickLabel',{'1k','10k','100k'}, 'GridAlpha',0.5);
            hold(hAx2,'on');
            hp = polarplot(hAx2,windDirs*pi/180,log10(altitudes),'yo','MarkerSize',2);