MATLAB: How to delete a struct

MATLABstructures

Hi, I am trying to make a predator-prey simulation and I've mapped structs in containers. One struct is one animal and the container represents either the predator or the prey. Now I want a prey to be eaten when it moves within a certain range of a predator. How do I delete a struct? Be easy on me, I'm a bit new to MATLAB. (;
Here's the code: the important part is below %ROOFDIEREN —> %ETEN.
% VARIABELEN
numDays = 50;
geboortekansPrey = 0.00;
geboortekansPred = 0.00;
minleeftijdPrey = 10; 
minleeftijdPred = 10; 
axis = 100;
W = 0:1:axis;
r = 2;
% MAPPEN MET INITIËLE DIEREN
predMap = containers.Map('KeyType', 'double', 'ValueType', 'any');
pred = struct('x', 1, 'y', 1, 'age', 25);
predMap(1) = pred;
preyMap = containers.Map('KeyType', 'double', 'ValueType', 'any');
prey = struct('x', 2, 'y', 2, 'age', 15);
preyMap(1) = prey;
prey = struct('x', 3, 'y', 3, 'age', 20);
preyMap(2) = prey;
% DAGEN
for t = 1:numDays
    disp(['day ', num2str(t),':']);
        
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%



% PROOIDIEREN
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    
    disp('Prooidieren:');
    for p = 1:length(preyMap)
        newPrey = preyMap(p);
% COÖRDINATEN

        d = rand * r;
        rad = rand * 2 * pi;
        
        newpreyx = newPrey.x + cos(rad) * d;
        newpreyy = newPrey.y + sin(rad) * d;
        
        while newpreyx<0 || newpreyx>axis || newpreyy<0 || newpreyy>axis
            d = rand * r;
            rad = rand * 2 * pi;
            newpreyx = newPrey.x + cos(rad) * d;       
            newpreyy = newPrey.y + sin(rad) * d;
        end
                     
        newPrey.x = newpreyx;
        newPrey.y = newpreyy;
        
% LEEFTIJD

        newPrey.age = newPrey.age + 1;
        
        preyMap(p) = newPrey;
        
% WEERGAVE

        Leeftijd = sprintf('Leeftijd: %d', preyMap(p).age);
        disp(Leeftijd) 
        Plaats = sprintf('Coördinaten: (%d, %d)', preyMap(p).x, preyMap(p).y);
        disp(Plaats)
        
        
% GEBOORTE

        if preyMap(p).age > minleeftijdPrey
           out=rand;
            if out<geboortekansPrey
                prey = struct('x', W(randi([1,numel(W)])), 'y', W(randi([1,numel(W)])), 'age', 0);
                preyMap(length(preyMap) + 1) = prey;      
            end    
        end            
    end
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% ROOFDIEREN
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    
    disp('Roofdieren:');
    for q = 1:length(predMap)
        newPred = predMap(q);
        
% COÖRDINATEN
        d = rand * r;
        rad = rand * 2 * pi;
        
        newpredx = newPred.x + cos(rad) * d;
        newpredy = newPred.y + sin(rad) * d;
        
        while newpredx<0 || newpredx>axis || newpredy<0 || newpredy>axis
            d = rand * r;
            rad = rand * 2 * pi;
            newpredx = newPred.x + cos(rad) * d;       
            newpredy = newPred.y + sin(rad) * d;
        end
                     
        newPred.x = newpredx;
        newPred.y = newpredy;
        
        
% LEEFTIJD
        newPred.age = newPred.age + 1;
        
% ETEN
        if abs(newPred.x - newPrey.x)<v && abs(newPred.y - newPrey.y)<v
            delete??????
        end
       
        predMap(q) = newPred;
        
% WEERGAVE
        Leeftijd = sprintf('Leeftijd: %d', predMap(q).age);
        disp(Leeftijd) 
        Plaats = sprintf('Coördinaten: (%d, %d)', predMap(q).x, predMap(q).y);
        disp(Plaats)
        
% GEBOORTE
        if predMap(q).age > minleeftijdPred
           out=rand;
            if out<geboortekansPred
                pred = struct('x', W(randi([1,numel(W)])), 'y', W(randi([1,numel(W)])), 'age', 0);
                predMap(length(predMap) + 1) = prey;      
            end    
        end            
    end
end

Best Answer

If my guesses are correct, the code below should be close to what you need.
%replace this
if abs(newPred.x - newPrey.x)<v && abs(newPred.y - newPrey.y)<v
    delete??????
end
%with this
for p=numel(preyMap):-1:1%loop backwards
    newPrey=preyMap(p);
    if hypot(newPred.x - newPrey.x,newPred.y - newPrey.y)<v
        preyMap(p)=[];%remove entry
    end
end
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