Matlab draws radar chart (four lines of code)

Actually, the radar chart is quite simple ！ Just four lines of code . Though very short , Because it is a single group of radar pictures , If you want to draw multiple groups of paintings , Write a hold on Just keep drawing .

Single group data radar chart ：

data = [2000,10000,8000,10667,6250,8667,7500,6000];
lim = [0,10000;0,10000;0,10000;0,10000;0,10000;0,10000;0,10000;0,10000];% Range of each data 
labels = {'1 Number ','2 Number ','3 Number ','4 Number ','5 Number ','6 Number ','7 Number ','8 Number '};% Name 
draw_radar(data,lim,labels);

  Radar maps of multiple sets of data ： If you want to distinguish easily , Just draw colors in the picture window by yourself , Mainly, I can't use color , Embarrassed .

data = [2000,10000,8000,10000,6250,8667,7500,6000];
lim = [0,10000;0,10000;0,10000;0,10000;0,10000;0,10000;0,10000;0,10000];% Range of each data 
labels = {'1 Number ','2 Number ','3 Number ','4 Number ','5 Number ','6 Number ','7 Number ','8 Number '};% Name 
draw_radar(data,lim,labels);
hold on
data = [3000,8000,7000,8000,7250,6667,7400,8000];
lim = [0,10000;0,10000;0,10000;0,10000;0,10000;0,10000;0,10000;0,10000];% Range of each data 
labels = {'1 Number ','2 Number ','3 Number ','4 Number ','5 Number ','6 Number ','7 Number ','8 Number '};% Name 
draw_radar(data,lim,labels);

Of course, there are functions , There is no need to understand , Anyway, you can't understand . On the last line draw_radar It's just a function . as follows ： Remember to change the file name to draw_radar Oh , Otherwise, the program will not run .

Don't you like it in front of the screen ？

function draw_radar(data,lim,labels)
    n=length(data);
    adj_data=zeros(n,1);
    point=zeros(n,2);
    set(gca,'units','normal','pos',[0 0 1 1]);
    axis off
    axis equal
    hold on
    theta_last=pi/2;
    for i=1:n
        theta=2*pi/n*i+pi/2;
        plot([0,500*cos(theta)],[0,500*sin(theta)],'k-','linewidth',2);
        for j=1:5
           plot([j*100*cos(theta_last),j*100*cos(theta)],[j*100*sin(theta_last),j*100*sin(theta)],'--','linewidth',0.75,'color',[0.5,0.5,0.5]);
        end
        theta_last=theta;
        if data(i)<lim(i,1)
            adj_data(i)=0;
        elseif data(i)>lim(i,2)
            adj_data(i)=500;
        else
            adj_data(i)=(data(i)-lim(i,1))/(lim(i,2)-lim(i,1))*500;
        end
        point(i,1:2)=[adj_data(i)*cos(theta);adj_data(i)*sin(theta)];
        text_around(510*cos(theta),510*sin(theta),labels{i},theta);
    end
    
    for i=1:n
        theta=2*pi/n*i+pi/2;
        for j=1:5
            text_around(j*100*cos(theta),j*100*sin(theta),num2str(lim(i,1)+(lim(i,2)-lim(i,1))/5*j),theta+pi/2,7);
        end
    end
    plot([point(:,1);point(1,1)],[point(:,2);point(1,2)],'k-','linewidth',0.8);
    fill(point(:,1),point(:,2),[0.9 0.9 0.7])
    alpha(0.5);
    texts=findobj(gca,'Type','Text');
    minx=-300;
    maxx=300;
    miny=-300;
    maxy=300;
    for i=1:length(texts)
        rect=get(texts(i),'Extent');
        x=rect(1);
        y=rect(2);
        dx=rect(3);
        dy=rect(4);
        if x<minx
            minx=x;
        elseif x+dx>maxx
            maxx=x+dx;
        end
        if y<miny
            miny=y;
        elseif y+dy>maxy
            maxy=y+dy;
        end
    end
    axis([minx-50,maxx+50,miny-20,maxy+20]);
end
function text_around(x,y,txt,theta,fontsize)
    if nargin==4
        fontsize=10;
    end
    section=mod(theta+pi/12,2*pi);
    if section>pi+pi/6
        if section>1.5*pi+pi/6
            text(x,y,txt,'VerticalAlignment','cap','HorizontalAlignment','left','Fontsize',fontsize);
        elseif section>1.5*pi
            text(x,y,txt,'VerticalAlignment','cap','HorizontalAlignment','center','Fontsize',fontsize);
        else
            text(x,y,txt,'VerticalAlignment','cap','HorizontalAlignment','right','Fontsize',fontsize);
        end
    elseif section>pi
        text(x,y,txt,'VerticalAlignment','middle','HorizontalAlignment','right','Fontsize',fontsize);
    elseif section>pi/6
        if section>0.5*pi+pi/6
            text(x,y,txt,'VerticalAlignment','bottom','HorizontalAlignment','right','Fontsize',fontsize);
        elseif section>0.5*pi
            text(x,y,txt,'VerticalAlignment','bottom','HorizontalAlignment','center','Fontsize',fontsize);
        else
            text(x,y,txt,'VerticalAlignment','bottom','HorizontalAlignment','left','Fontsize',fontsize);
        end
    else
        text(x,y,txt,'VerticalAlignment','middle','HorizontalAlignment','left','Fontsize',fontsize);
    end
end

Expand the ： 

radar , It's English Radar transliteration , From the radio detection and ranging Abbreviation , You mean for “ Radio detection and ranging ”, That is to use radio methods to find targets and determine their spatial position . therefore , Radar is also called “ Radio location ”. Radar is an electronic device that uses electromagnetic waves to detect targets . Radar emits electromagnetic wave to irradiate the target and receives its echo , Thus, the distance from the target to the electromagnetic wave emission point is obtained 、 The rate of distance change （ Radial velocity ）、 bearing 、 Height, etc .

The emergence of radar , It is because during the first World War, when Britain and Germany were at war , Britain is in urgent need of a radar that can detect metal objects in the air （ technology ） It can help search for German aircraft in the anti air attack war . During the second world war , Radar has already appeared ground to air 、 air-to-ground （ Search for ） bombardment 、 Air to air （ Volley ） Fire control 、 Radar technology of IFF function .

After world war ii , Radar has developed monopulse angle tracking 、 Pulse Doppler signal processing 、 High resolution of synthetic aperture and pulse compression 、 Combined system combining IFF 、 Automatic fire control system combined with computer 、 Terrain avoidance and terrain following 、 Passive or active phase array 、 Frequency agility 、 New radar systems such as multi-target detection and tracking .

Later, with the scientific progress of microelectronics and other fields , The continuous development of Radar Technology , Its connotation and research content are constantly expanding . The detection method of radar has been developed from the former only radar detector to infrared light 、 ultraviolet 、 Laser and other optical detection means are integrated and coordinated .

The multi-function capability of contemporary radar makes battlefield commanders search in various ways / Scan the target in tracking mode , And automatically correct the interference error , And most of the control functions are completed inside the system .

Automatic target recognition can maximize the role of weapon systems , AWACS and JSTARS Such an integrated radar system with the ability to identify the enemy and me in the battlefield has actually become the information command center in the future battlefield .

application ：

The advantage of radar is that it can detect long-distance targets day and night , And free from fog 、 Clouds and rain block , All weather 、 The characteristics of the whole day , And have a certain penetration ability . therefore , It has not only become an indispensable electronic equipment in military , And it is widely used in social and economic development ( Such as weather forecast 、 Resource exploration 、 Environmental monitoring, etc ) And scientific research ( Celestial research 、 Atmospheric physics 、 Research on ionospheric structure, etc ). Spaceborne and airborne synthetic aperture radar has become a very important sensor in remote sensing . Radar targeting the ground can detect the precise shape of the ground . Its spatial resolution can reach several meters to tens of meters , And it has nothing to do with distance . Radar is monitoring flood 、 Sea ice monitoring 、 Soil moisture survey 、 Forest resources inventory 、 Geological survey and other aspects also show good application potential .