非常实用的遗传算法工具箱

% MIGRATE.M (MIGRATion of individuals between subpopulations) % % This function performs migration of individuals. % % Syntax: [Chrom, ObjV] = migrate(Chrom, SUBPOP, MigOpt, ObjV) % % Input parameters: % Chrom - Matrix containing the individuals of the current % population. Each row corresponds to one individual. % SUBPOP - Number of subpopulations % MigOpt - (optional) Vector containing migration parameters % MigOpt(1): MIGR - Rate of individuals to be migrated per % subpopulation (% of subpopulation) % if omitted or NaN, 0.2 (20%) is assumed % MigOpt(2): Select - number indicating the selection method % of replacing individuals % 0 - uniform selection % 1 - fitness-based selection (replace worst % individuals) % if omitted or NaN, 0 is assumed % MigOpt(3): Structure - number indicating the structure % of the subpopulations for migration % 0 - net structure (unconstrained migration) % 1 - neighbourhood structure % 2 - ring structure % if omitted or NaN, 0 is assumed % ObjV - (optional) Column vector containing the objective values % of the individuals in the current population, needed for % fitness-based migration, this saves the % recalculation of objective values for population. % % Output parameters: % Chrom - Matrix containing the individuals of the current % population after migration. % ObjV - if ObjV is input parameter, than column vector containing % the objective values of the individuals of the current % generation after migration. % Author: Hartmut Pohlheim % History: 16.02.94 file created % 18.02.94 comments at the beginning added % exchange of ObjV too % 25.02.94 clean up % 26.02.94 ObjV optional input parameter % Select and Structure added, parameter reordered % 17.03.94 renamed to migrate.m, more parameter checks function [Chrom, ObjV] = migrate(Chrom, SUBPOP, MigOpt, ObjV); % Check parameter consistency if nargin < 2, error('Input parameter SUBPOP missing'); end if (nargout == 2 & nargin < 4), error('Input parameter ObjV missing'); end [Nind, Nvar] = size(Chrom); if length(SUBPOP) ~= 1, error('SUBPOP must be a scalar'); end if SUBPOP == 1, return; end if (Nind/SUBPOP) ~= fix(Nind/SUBPOP), error('Chrom and SUBPOP disagree'); end NIND = Nind/SUBPOP; % Compute number of individuals per subpopulation if nargin > 3, [mO, nO] = size(ObjV); if nO ~= 1, error('ObjV must be a column vector'); end if Nind ~= mO, error('Chrom and ObjV disagree'); end IsObjV = 1; else IsObjV = 0; ObjV = []; end if nargin < 3, MIGR = 0.2; Select = 0; Structure = 0; end if nargin > 2, if isempty(MigOpt), MIGR = 0.2; Select = 0; Structure = 0; elseif isnan(MigOpt), MIGR = 0.2; Select = 0; Structure = 0; else MIGR = NaN; Select = NaN; Structure = NaN; if length(MigOpt) > 3, error('Parameter MigOpt is too long'); end if length(MigOpt) >= 1, MIGR = MigOpt(1); end if length(MigOpt) >= 2, Select = MigOpt(2); end if length(MigOpt) >= 3, Structure = MigOpt(3); end if isnan(MIGR), MIGR =0.2; end if isnan(Select), Select = 0; end if isnan(Structure), Structure = 0; end end end if (MIGR < 0 | MIGR > 1), error('Parameter for migration rate must be a scalar in [0 1]'); end if (Select ~= 0 & Select ~= 1), error('Parameter for selection method must be 0 or 1'); end if (Structure < 0 | Structure > 2), error ('Parameter for structure must be 0, 1 or 2'); end if (Select == 1 & IsObjV == 0), error('ObjV for fitness-based migration needed');end if MIGR == 0, return; end MigTeil = max(floor(NIND * MIGR), 1); % Number of individuals to migrate % Perform migration between subpopulations --> create a matrix for migration % in every subpopulation from best individuals of the other subpopulations % Clear storing matrices ChromMigAll = []; if IsObjV == 1, ObjVAll = []; end % Create matrix with best/uniform individuals of all subpopulations for irun = 1:SUBPOP % sort ObjV of actual subpopulation if Select == 1, % fitness-based selection [Dummy, IndMigSo]=sort(ObjV((irun-1)*NIND+1:irun*NIND)); else % if Select == 0 % uniform selection [Dummy, IndMigSo]=sort(rand(NIND, 1)); end % take MigTeil (best) individuals, copy individuals and objective values IndMigTeil=IndMigSo(1:MigTeil)+(irun-1)*NIND; ChromMigAll = [ChromMigAll; Chrom(IndMigTeil,:)]; if IsObjV == 1, ObjVAll = [ObjVAll; ObjV(IndMigTeil,:)]; end end % perform migration for irun = 1:SUBPOP ChromMig = ChromMigAll; if IsObjV == 1, ObjVMig = ObjVAll; end if Structure == 1, % neighbourhood % select individuals of neighbourhood subpopulations for ChromMig and ObjVMig popnum = [SUBPOP 1:SUBPOP 1]; ins1 = popnum(irun); ins2 = popnum(irun + 2); InsRows = [(ins1-1)*MigTeil+1:ins1*MigTeil (ins2-1)*MigTeil+1:ins2*MigTeil]; ChromMig = ChromMig(InsRows,:); if IsObjV == 1, ObjVMig = ObjVMig(InsRows,:); end elseif Structure == 2, % ring % select individuals of actual-1 subpopulation for ChromMig and ObjVMig popnum = [SUBPOP 1:SUBPOP 1]; ins1 = popnum(irun); InsRows = (ins1-1)*MigTeil+1:ins1*MigTeil; ChromMig = ChromMig(InsRows,:); if IsObjV == 1, ObjVMig = ObjVMig(InsRows,:); end else % if Structure == 0, % complete net % delete individuals of actual subpopulation from ChromMig and ObjVMig DelRows = (irun-1)*MigTeil+1:irun*MigTeil; ChromMig(DelRows,:) = []; if IsObjV == 1, ObjVMig(DelRows,:) = []; end end % Create an index from a sorted vector with random numbers [Dummy,IndMigRa]=sort(rand(size(ChromMig,1),1)); % Take MigTeil numbers from the random vector IndMigN=IndMigRa((1:MigTeil)'); % copy MigTeil individuals into Chrom and ObjV Chrom((1:MigTeil)+(irun-1)*NIND,:) = ChromMig(IndMigN,:); if IsObjV == 1, ObjV((1:MigTeil)+(irun-1)*NIND,:) = ObjVMig(IndMigN,:); end end % End of function