📄 ga.htmk
字号:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN">
<HTML>
<HEAD>
<TITLE>Genetic Algorithms toolbox for Matlab</TITLE>
<META NAME="GENERATOR" CONTENT="Mozilla/3.0Gold (WinNT; I) [Netscape]">
</HEAD>
<BODY BGCOLOR="#FFFFFF">
<H2>Genetic Algorithms toolbox for Matlab (by Michael B. Gordy)</H2>
<PRE>From: <A HREF="mailto:m1mbg00@newfed.frb.gov">m1mbg00@newfed.frb.gov</A> (Michael B Gordy)
Reply-To: <A HREF="mailto:m1mbg00@frb.gov">m1mbg00@frb.gov
</A>Newsgroups: comp.ai.genetic,comp.soft-sys.matlab
Subject: Re: Genetic Algorithms toolbox for Matlab
Date: Wed, 7 Feb 1996 17:08:52 GMT
Organization: Federal Reserve Board
Message-ID: DMF0yt.ACr@glendora.uucp
References: 4edofo$j19@ftp.ee.vill.edu 4ekssr$pjp@bond.nexus.se
There seems to be much unmet demand for a GA routine in Matlab, so I'll
make mine available. It's easy to use, as its syntax is fairly close
to Matlab's fmins routine. It works, but I can't make any claims for
sophistication. (Hey, I'm an economist, not a computer scientist, and
I don't follow the GA literature closely.)
Use at your own risk, of course. I can't provide support in any formal
sense, but would be happy to try to incorporate suggested improvements.
-- Michael Gordy
Federal Reserve Board</PRE>
<PRE>
<HR WIDTH="100%"></PRE>
<PRE><B>View/Download</B> <I>renamed</I> Matlab file <A HREF="gagordy.m">gagordy.m</A> (identical to ga.m below)</PRE>
<PRE>
<HR WIDTH="100%">% ----------------------- cut here for ga.m -------------------------
function [beta,stopcode]=ga(funstr,parspace,options,p1,p2,p3,p4,p5,p6,p7,p8,p9)
%[beta,stopcode]=ga(funstr,parspace,options,p1,p2,p3,p4,p5,p6,p7,p8,p9)
% Genetic Algorithm for function maximization.
% Especially useful for functions with kinks and discontinuities,
% and where a good "starting point" is unavailable.
% See Dorsey and Mayer,
% Journal of Business and Economic Statistics, January 1995, 13(1)
% Program by Michael Gordy <<A HREF="mailto:m1mbg00@frb.gov">m1mbg00@frb.gov</A>>
% Version 1.12, 7 February 1996
%
% OUTPUTS:
% beta = (1 x K) parameter vector maximizing funstr
% stopcode = code for terminating condition
% == 1 if terminated normally
% == 2 if maximum number of iterations exceeded
%
% INPUTS:
% funstr = name of function to be maximized (string).
% parspace = (2 x K) matrix is [min; max] of parameter space dimensions
% or, if (3 x K), then bottom row is a good starting value
% options = vector of option settings
% p1,p2,...,p9 are optional parameters to be passed to funstr
%
% where:
% options(1) = m (size of generation, must be even integer)
% options(2) = eta (crossover rate in (0,1); use Booker's VCO if < 0)
% options(3) = gamma (mutation rate in (0,1))
% options(4) = printcnt (print status once every printcnt iterations)
% Set printcnt to zero to suppress printout.
% options(5) = maxiter (maximum number of iterations)
% options(6) = stopiter (minimum number of gains < epsln before stop)
% options(7) = epsln (smallest gain worth recognizing)
% options(8) = rplcbest (every rplcbest iterations, insert best-so-far)
% options(9) = 1 if function is vectorized (i.e., if the function
% can simultaneously evaluate many parameter vectors).
% Default option settings: [20,-1,0.12,10,20000,2000,1e-4,50,0]
%
% Note:
% The function is maximized with respect to its first parameter,
% which is expressed as a row vector.
% Example:
% Say we want to maximize function f with respect to vector p,
% and need also to pass to f data matrices x,y,z. Then,
% write the function f so it is called as f(p,x,y,z). GA will
% assume that p is a row vector.
gaver='1.12';
defopt=[24,-1,0.12,10,20000,2000,1e-4,50,0];
months = ['Jan';'Feb';'Mar';'Apr';'May';'Jun';...
'Jul';'Aug';'Sep';'Oct';'Nov';'Dec'];
if nargin>2
if isempty(options)
options=defopt;
end
else
options=defopt;
end
m=options(1); eta=options(2); gam=options(3);
printcnt=options(4);
maxiter=options(5);
stopiter=options(6); epsln=options(7);
rplcbest=options(8);
vecfun=options(9);
% Use Booker's VCO if eta==-1
vco=(eta<0); eta=abs(eta);
% Cancel rplcbest if <=0
if rplcbest<=0, rplcbest=maxiter+1; end
K=size(parspace,2);
% Draw initial Generation
G=rand(m,K).*(parspace(2*ones(m,1),:)-parspace(ones(m,1),:))...
+parspace(ones(m,1),:);
b0rows=size(parspace,1)-2;
if b0rows>0
G(1:b0rows,:)=parspace(3:b0rows+2,:);
parspace=parspace([1 2],:);
end
% Initial 'best' holders
inarow=0;
bestfun=-Inf; beta=zeros(1,K);
% Score for each of m vectors
f=zeros(m,1);
% Setup function string for evaluations
paramstr=',p1,p2,p3,p4,p5,p6,p7,p8,p9';
evalstr = [funstr,'(G'];
if ~vecfun
evalstr=[evalstr, '(i,:)'];
end
if nargin>3, evalstr=[evalstr,paramstr(1:3*(nargin-3))]; end
evalstr = [evalstr, ')'];
% Print header
if printcnt>0
disp(['GA (Genetic Algorithm), Version ',gaver,' by Michael Gordy'])
disp(['Maximization of function ',funstr])
disp('i = Current generation')
disp('best_i = Best function value in generation i')
disp('best = Best function value so far')
disp('miss = Number of generations since last hit')
disp('psi = Proportion of unique genomes in generation')
disp(sprintf(['\n',blanks(20),'i best_i best miss psi']))
end
iter=0; stopcode=0;
oldpsi=1; % for VCO option
while stopcode==0
iter=iter+1;
% Call function for each vector in G
if vecfun
f=eval(evalstr);
else
for i=1:m
f(i)=eval(evalstr);
end
end
f0=f;
[bf0,bx]=max(f);
bf=max([bf0 bestfun]);
fgain=(bf-bestfun);
if fgain>epsln
inarow=0;
else
inarow=inarow+1;
end
if fgain>0
bestfun=bf;
beta=G(bx(1),:);
end
if printcnt>0 & rem(iter,printcnt)==1
psi=length(unique(G))/m;
ck=clock;
ckhr=int2str(ck(4)+100); ckday=int2str(ck(3)+100);
ckmin=int2str(ck(5)+100); cksec=int2str(ck(6)+100);
timestamp=[ckday(2:3),months(ck(2),:),' ',...
ckhr(2:3),':',ckmin(2:3),':',cksec(2:3),' '];
disp([timestamp,sprintf('%6.0f %8.5e %8.5e %5.0f %5.3f',...
[iter bf0 bestfun inarow psi])])
save gabest beta timestamp iter funstr
end
% Reproduction
f=(f-min(f)).^(1+log(iter)/100);
pcum=cumsum(f)/sum(f);
r=rand(1,m); r=sum(r(ones(m,1),:)>pcum(:,ones(1,m)))+1;
G=G(r,:);
% Crossover
if vco
psi=length(unique(G))/m;
eta=max([0.2 min([1,eta-psi+oldpsi])]);
oldpsi=psi;
end
y=sum(rand(m/2,1)<eta);
if y>0
% choose crossover point
x=floor(rand(y,1)*(K-1))+1;
for i=1:y
tmp=G(i,x(i)+1:K);
G(i,x(i)+1:K)=G(i+m/2,x(i)+1:K);
G(i+m/2,x(i)+1:K)=tmp;
end
end
% Mutation
M=rand(m,K).*(parspace(2*ones(m,1),:)-parspace(ones(m,1),:))...
+parspace(ones(m,1),:);
domuta=find(rand(m,K)<gam);
G(domuta)=M(domuta);
% Once every rplcbest iterations, re-insert best beta
if rem(iter,rplcbest)==0
G(m,:)=beta;
end
stopcode=(inarow>stopiter)+2*(iter>maxiter);
end
if printcnt>0
if stopcode==1
disp(sprintf('GA: No improvement in %5.0f generations.\n',stopiter))
else
disp(sprintf('GA: Maximum number of iterations exceeded.\n'))
end
end
% end of GA.M
<HR></PRE>
<ADDRESS>created by: <A HREF="mailto:rauth@tyche.mat.univie.ac.at">Mitch
Rauth</A> (last changed 10. May 1996)</ADDRESS>
<ADDRESS>updated and changed by: <A HREF="../index.html">Hartmut Pohlheim</A>
(September 1996)</ADDRESS>
</BODY>
</HTML>
⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -