MATLAB Examples

Contents

Examples

The following examples illustrate the application of the function polarPcolor

clearvars;close all;clc;

Minimalist example

Assuming that a remote sensor is measuring the wind field for a radial distance ranging from 50 to 1000 m. The scanning azimuth is oriented from North (0 deg) to North-North-East ( 80 deg):

R = linspace(50,1000,100)./1000; % (distance in km)
Az = linspace(0,80,100); % in degrees
[~,~,windSpeed] = peaks(100); % radial wind speed
figure
[h,c]=polarPcolor(R,Az,windSpeed)
h = 

  Surface with properties:

       EdgeColor: 'none'
       LineStyle: '-'
       FaceColor: 'flat'
    FaceLighting: 'flat'
       FaceAlpha: 1
           XData: [100x100 double]
           YData: [100x100 double]
           ZData: [100x100 double]
           CData: [100x100 double]

  Use GET to show all properties


c = 

  ColorBar with properties:

    Location: 'westoutside'
      Limits: [-5.3237 6.8662]
    FontSize: 9
    Position: [0.1772 0.1095 0.0476 0.8167]
       Units: 'normalized'

  Use GET to show all properties

Example with options

We want to have 4 circles and 7 spokes, and to give a label to the
radial coordinate
figure
[~,c]=polarPcolor(R,Az,windSpeed,'labelR','r (km)','Ncircles',4,'Nspokes',7);
ylabel(c,' radial wind speed (m/s)');
set(gcf,'color','w')

Dealing with outliers

We introduce outliers in the wind velocity data. These outliers are represented as wind speed sample with a value of 100 m/s. These corresponds to unrealistic data that need to be ignored. To avoid bad scaling of the colorbar, the function polarPcolor uses the function caxis combined to the function quantile to keep the colorbar properly scaled: caxis([quantile(Z(:),0.01),quantile(Z(:),0.99)])

windSpeed(1:10:end,1:20:end)=100;

figure
[~,c]=polarPcolor(R,Az,windSpeed);
ylabel(c,' radial wind speed (m/s)');
set(gcf,'color','w')

polarPcolor without colorbar

The colorbar is activated by default. It is possible to remove it by using the option 'colBar'. When the colorbar is desactivated, the outliers are not "removed" and bad scaling is clearly visible:

figure
polarPcolor(R,Az,windSpeed,'colBar',0) ;

Different geometry 1

N = 360;
R = linspace(0,1000,N)./1000; % (distance in km)
Az = linspace(0,360,N); % in degrees
[~,~,windSpeed] = peaks(N); % radial wind speed
figure
[~,c]= polarPcolor(R,Az,windSpeed);
ylabel(c,' radial wind speed (m/s)');
set(gcf,'color','w')

Different geometry 2

N = 360;
R = linspace(500,1000,N)./1000; % (distance in km)
Az = linspace(0,270,N); % in degrees
[~,~,windSpeed] = peaks(N); % radial wind speed
figure
[~,c]= polarPcolor(R,Az,windSpeed,'Ncircles',3);
location = 'NorthOutside';
ylabel(c,' radial wind speed (m/s)');
set(c,'location',location);
set(gcf,'color','w')