Operator '<' is not supported for operands of type 'struct'.

When I test this code which is shown below. I got an error of " Operator '<' is not supported for operands of type 'struct'. "

Error in untitled2 (line 157)

if NewSol.Cost < pop(i).Cost

. How can i solve this error?

clc;

clear all;

close all;

%% Problem Definition

% [lb,ub,D,fobj] = Get_Functions_details(Function_name); % The shifted functions' information

D = 2; % Number of Decision Variables

lb1=[2 0.001];

ub1=[33 0.5 ];

[ sLOSS,Busvoltage]=power_flow1()

n = 200; % Population Size

m = 2; % Number of search agenets in a group

%% Generate initial population of cheetahs (Algorithm 1, L#2)

empty_individual.Position = [];

empty_individual.Cost = [];

BestSol.Cost = sLOSS;

pop = repmat(empty_individual,n,1);

for i=1:n

pop(i).Position = lb1+rand.*(ub1-lb1);

pop(i).Position(1) = round(pop(i).Position(1));

end

for i=1:n

pop(i).Cost = power_flow_DG(pop(i).Position(1),pop(i).Position(2))

if pop(i).Cost < BestSol.Cost

BestSol.Cost = pop(i).Cost; % Initial leader position

end

end

%% Initialization (Algorithm 1, L#3)

pop1 = pop; % Population's initial home position

BestCost = []; % Leader fittnes value in a current hunting period

X_best = BestSol; % Prey solution sofar

Globest = BestCost; % Prey fittnes value sofar

%% Initial parameters

t = 0; % Hunting time counter (Algorithm 1, L#4)

it = 1; % Iteration counter(Algorithm 1, L#5)

MaxIt = D*10000; % Maximum number of iterations (Algorithm 1, L#6)

T = ceil(D/10)*60; % Hunting time (Algorithm 1, L#7)

FEs = 0; % Counter for function evaluations (FEs)

%% CO Main Loop

while FEs <= MaxIt % Algorithm 1, L#8

m = 1+randi (ceil(n/2));

i0 = randi(n,1,m); % select a random member of cheetahs (Algorithm 1, L#9)

for k = 1 : m % Algorithm 1, L#10

i = i0(k);

% neighbor agent selection (Algorithm 1, L#11)

if k == length(i0)

a = i0(k-1);

else

a = i0(k+1);

end

X = pop(i).Position; % The current position of i-th cheetah

X1 = pop(a).Position; % The neighbor position

Xb = BestSol%.Position; % The leader position

Xbest = X_best%.Position;% The pery position

kk=0;

% Uncomment the follwing statements, it may improve the performance of CO

if i<=2 && t>2 && t>ceil(0.2*T+1) && abs(BestCost(t-2)-BestCost(t-ceil(0.2*T+1)))<=0.0001*Globest(t-1)

X = X_best.Cost;

kk = 0;

elseif i == 3

X = BestSol.Cost;

kk = -0.1*rand*t/T;

else

kk = 0.25;

end

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

if mod(it,100)==0 || it==1

xd = randperm(numel(X));

end

Z = X;

%% Algorithm 1, L#12

for j = 1:1 % select arbitrary set of arrangements

%% Algorithm 1, L#13

r_Hat = randn; % Randomization paameter, Equation (1)

r1 = rand;

if k == 1 % The leader's step length (it is assumed that k==1 is associated to the leade number)

alpha = 0.001*t/T.*(ub1(j)-lb1(j)); % Step length, Equation (1) %This can be updated by desired equation

else % The members' step length

%alpha = 0.001 * t / T * abs(Xb.j - X.j) + 0.001 * round(double(rand > 0.9));

alpha = 0.001*t/T*abs(Xb(j).Cost-X(j))+0.001.*round(double(rand>0.9));%member step length, Equation (1)%This can be updated by desired equation

end

r = randn;

r_Check = abs(r).^exp(r/2).*sin(2*pi*r); % Turning factor, Equation (3)%This can be updated by desired equation

beta = X1(j)-X(j); % Interaction factor, Equation (3)

h0 = exp(2-2*t/T);

H = abs(2*r1*h0-h0);

%% Algorithm 1, L#14

r2 = rand;

r3 = kk+rand;

%% Strategy selection mechanism

if r2 <= r3 % Algorithm 1, L#15

r4 = 3*rand; % Algorithm 1, L#16

if H > r4 % Algorithm 1, L#17

Z(j) = X(j)+r_Hat.^-1.*alpha; % Search, Equation(1) (Algorithm 1, L#18)

else

Z(j) = Xbest(j).Cost+r_Check.*beta; % Attack, Equation(3) (Algorithm 1, L#20)

end

else

Z(j) = X(j); % Sit&wait, Equation(2) (Algorithm 1, L#23)

end

end

%% Update the solutions of member i (Algorithm 1, L#26)

% Check the limits

xx1=find(Z<lb1);

Z(xx1)=lb1(xx1)+rand(1,numel(xx1)).*(ub1(xx1)-lb1(xx1));

xx1=find(Z>ub1);

Z(xx1)=lb1(xx1)+rand(1,numel(xx1)).*(ub1(xx1)-lb1(xx1));

% Evaluate the new position

NewSol.Position = Z;

NewSol.Position(1)= round(NewSol.Position(1));

NewSol.Cost = power_flow_DG(NewSol.Position(1),NewSol.Position(2));

%NewSol.taille=pop.taille;

if NewSol.Cost < pop(i).Cost

pop(i).Cost = NewSol.Cost;

if pop(i).Cost < BestSol.Cost

BestSol = pop(i);

end

end

FEs = FEs+1;

end

t = t+1; % (Algorithm 1, L#28)

%% Leave the prey and go back home (Algorithm 1, L#29)

if t>T && t-round(T)-1>=1 && t>2

if abs(BestCost(t-1)-BestCost(t-round(T)-1))<=abs(0.01*BestCost(t-1))

% Change the leader position (Algorithm 1, L#30)

best = X_best.Cost;

j0=randi(D,1,ceil(D/10*rand));

% best(j0) = lb1(j0)+rand(1,length(j0)).*(ub1(j0)-lb1(j0));

BestSol.Cost = power_flow_DG(NewSol.Position(1),NewSol.Position(2));

BestSol.Position = best; % Leader's new position

FEs = FEs+1;

i0 = randi(n,1,round(1*n));

% Go back home, (Algorithm 1, L#30)

pop(i0(n-m+1:n)) = pop1(i0(1:m)); % Some members back their initial positions

pop(i).Cost = X_best; % Substitude the member i by the prey (Algorithm 1, L#31)

t = 1; % Reset the hunting time (Algorithm 1, L#32)

end

end

it = it +1; % Algorithm 1, L#34

%% Update the prey (global best) position (Algorithm 1, L#35)

if BestSol.Cost<X_best.Cost

X_best=BestSol;

end

BestCost(t)=BestSol.Cost;

Globest(1,t)=X_best.Cost;

%% Display

if mod(it,500)==0

disp([' FEs>> ' num2str(FEs) ' BestCost = ' num2str(Globest(t))]);

end

end

fit(run) = Globest(end) ;

mean_f = mean (fit);

std_f = std (fit);

% clc

toc

[Stephen23]

We cannot run your code because you have not provided us with power_flow1.m

But you can tell us the classes of the structure content that you are comparing.

Note that bdata33bus.m and ldata33busmod4.m are not runnable Mfies, and thus the .m extension is very misleading. You should simply use a .txt extension and e.g. READMATRIX to import their data.

Answer 1

[Constantino Carlos Reyes-Aldasoro]

Hard to know the exact issue without access to all the code and variables but most probably it is because you cannot compare a struct, all of it, just specific fields, look at the following code:

a=3;
b=[1 2 3];
c.a =1; c.b=2;
a>1

ans = logical
   1

b>1

ans = 1x3 logical array
   0   1   1

% the following will create an error so let's use a try-catch
try
    c>1
catch
    disp('Error will be Operator ''>'' is not supported for operands of type ''struct''. ')
end

Error will be Operator '>' is not supported for operands of type 'struct'. 

However, if you only try one field of the struct

c.a>1

ans = logical
   0

That works, so look at the variable that you are trying to compare withy < and see if it is a struct. Then see which fields you need to compare and that should fix the problem.