How Do I get Points in a given Plot?

Hello everybody,

I try to create the A star algorithm in MatLab using a Vektorfile with roads to get the best possible route.

I want to create an interactive plot that when the programm runs, you should select any point (with the mouse) on the map and then the route would appear.

Is it even possible?

close all
clear all
clc
format long g

% Straßen Importieren
load('all_geo.mat');

% A und L berechnen
[A,L] = shpToAdjMatrix(all);  
Id = L(:,1);
Lat = L(:,2);
Lon = L(:,3);
dist = L(:,4);

% Start und Ende definieren
start = 100; 
ende = 2000;

% Current Node
cn = start; % Current Node mit start value initialisieren

% Close und Open initialisieren 
closed = false(length(A),1);
open = [];

% Luftlinie h definieren mit der Formel der euklidischen Distanz
h = sqrt((Lat(:) - Lat(ende)).^2+(Lon(:) - Lon(ende)).^2);

% Vektor für Strecke von Ende zum Start definieren
g = zeros(length(Id),1);

% Vektor für Kosten setzen
f = zeros(length(Id),1);
f(:) = f(:) + 2000000;

% Vektor für Parentnode setzen
P  = zeros(length(Id),1);
P(cn) = -1000; % -1000 gilt als default Wert

    while true
        
        % Wenn Endknoten aus open entnommen wurde dann stop
        if (cn == ende)
            break;
            
        % Sonst alle Nachbarkanten in Adjazenzmatrix durchlaufen    
        else
            
            for i = 1 : length(A)
                
                if (A(i,cn) > 0 && closed(i) ~= true)
                    
                    % Kosten aus Luftlinie und Strecke zum Start berechnen
                    f_new = h(i) + A(i,cn) + g(cn);
                    
                    % Wenn kostenNew < konstenAlt dann aktualisieren
                    if f_new < f(i)
                        g(i) = g(cn) + A(i,cn);
                        P(i) = cn;
                        f(i) = f_new;

                        temp =  [i, f_new];
                        open = [temp; open];
                    end
                end
            end     
        end
        
        % Knoten in der Close Liste hinzufügen
        closed(cn) = true;
        
        % Current Node aus open entfernen
        open(open == cn, :) = [];
            
        % minimale Kosten finden und als neue cn definieren
        [~,newMin] = min(open(:,2));
        cn = open(newMin,1);
        
    end
    
% A* Route in knoten speichern
N = 1;   % counter
knots(1,1) = cn;
PKnot = cn; % parent knode
    
while(P(PKnot) ~= -1000)
    
    PKnot = P(PKnot);
    if P(PKnot) ~= 0
        knots(N,1) = PKnot;
        knots(N,2) = Lat(PKnot);
        knots(N,3) = Lon(PKnot);
    end
    
    N = N + 1;
end
    
% Plots
hold on
grid on
axis equal

% Karte plotten
% boston = plot(img, R);

% Straßen plotten
for i = 1:length(all)
    if all(i).CLASS >= 4 % Normale Straßenklassen = 4,5,6,7
        local = plot(all(i).X, all(i).Y, 'black', 'LineWidth', 1);
    elseif all(i).CLASS < 4 % Autobahnklassen = 1,2,3
        highways = plot(all(i).X, all(i).Y, 'red', 'LineWidth', 1.3);
    end
end

% Start und Ende markieren
[Lat,Lon] = getpts; % Start
plotST = plot(([Lat,Lon], 'og', 'LineWidth', 1.5, 'MarkerSize', 10));

plotStart = plot(Lat(start), Lon(start), 'og', 'LineWidth', 1.5, 'MarkerSize', 10);
plotEnde = plot(Lat(ende), Lon(ende), 'xg', 'LineWidth', 1.5, 'MarkerSize', 10);

for i = length(knots)-1:-1:-1
    % das er auch wirklich die Straße ab geht    
    if knots(i,1) > length(all)
        % Endpunkt abgerufen
        tempPosition = knots(i,1)-length(all);
        plotRoute = plot(all(tempPosition).X,all(tempPosition).Y, 'g-', 'LineWidth', 2);
    else
        % Startpunkt abgerufen
        plotRoute = plot(all(knots(i,1)).X,all(knots(i,1)).Y, 'g-', 'LineWidth', 2);
    end
end

Thanks in advance!

Answer 1

[Monisha Nalluru]

From my understanding, you want to user to select points in the plot, based on the selected points route would be ploted on existing figure.

Inorder to perform above operation, there is feature called brush which will help to fetch all the points which user has selected into workspace. In your algoritm while plotting map make

brush('on');

Once your selected the data there are couple of options in toolstrip inorder to export the points into command window, copy to clipboard or create a new variable in workspace

The other option is using ginput

[x,y]=ginput(n) %where n is number of points you want user to select

Hope this is helpful!

[Panagiotis Koutsikos]

Thank you for your helpful answer!