function NewChrom = recpoly(OldChrom, polyStruct)
% recpoly.m (RECombination POLYnomial)
%
% This function performs term group recombination between pairs of
% polynomial individuals and returns the new individuals after mating.
%
% Syntax: NewChrom = recpoly(OldChrom, polyStruct)
%
% Input parameters:
% OldChrom - Matrix containing the chromosomes of the old
% population. Each line corresponds to one
% individual
%
% polyStruct - A structure containing information about the polynomial
% to be fitted. There should be five members:
%
% tVars: column matrix of the independent variables of the
% data to be fitted
%
% tData: column vector the dependent variables
%
% vars: the number of variables (i.e. size(tVars,2))
%
% maxTerms: the maximum number of term groups to be used
%
% maxPower: the total maximum power of any term (i.e. the
% maximum that the sum of all of the powers in a term can
% be)
%
% Output parameter:
%
% NewChrom - Matrix containing the chromosomes of the population
% after mating, ready to be mutated and/or evaluated,
% in the same format as OldChrom.
%
% Author: Richard Crozier
% History: 11.11.2008 file created
a = zeros(polyStruct.maxTerms,1);
b = ones(polyStruct.maxTerms,1);
method = a;
myRands = randMat(a,b,method,size(OldChrom,1));
vars = polyStruct.vars;
NewChrom = zeros(size(OldChrom), 'int16');
for i = 1:2:size(OldChrom,1)
if i == size(OldChrom,1)
% If the number of individuals is odd, we can't mate the last
% one, so we just return it to the population, bad luck big
% fella.
NewChrom(i,:) = OldChrom(i,:);
return;
end
ChildTermCnt_1 = 1;
ChildTermCnt_2 = 1;
n = 1;
% first allocate the first parents terms randomly, checking that
% the terms exist first
for j = 1:vars+1:size(OldChrom,2)
if OldChrom(i,j) == 1
newrand = rand(1,1);
if (ChildTermCnt_2 > size(OldChrom,2) && ChildTermCnt_1 < size(OldChrom,2)) || newrand > myRands(i,n)
n = n + 1;
NewChrom(i,ChildTermCnt_1:ChildTermCnt_1+vars) = OldChrom(i,j:j+vars);
ChildTermCnt_1 = ChildTermCnt_1 + vars + 1;
elseif (ChildTermCnt_1 > size(OldChrom,2) && ChildTermCnt_2 < size(OldChrom,2)) || newrand <= myRands(i,n)
n = n + 1;
NewChrom(i+1,ChildTermCnt_2:ChildTermCnt_2+vars) = OldChrom(i,j:j+vars);
ChildTermCnt_2 = ChildTermCnt_2 + vars + 1;
else
error('more terms needed to be allocated, but both polynomials are full, this should not happen')
end
end
end
% Now allocate the second parents terms, randomly if the term does
% not already exist in the child chromosome
n = 1;
for j = 1:vars+1:size(OldChrom,2)
if OldChrom(i+1,j) == 1
if ChildTermCnt_2 == 1 && ChildTermCnt_1 == 1
% no terms allocated yet (very strange?) so termTest = 0
termTest = 0;
elseif ChildTermCnt_1 == 1
% no terms allocated to child 1 yet, so use dummy
% chromosome part consisting of all -1 values
termTest = HasTerm((-1*ones(1,vars+1)), NewChrom(i+1,1:ChildTermCnt_2-1), OldChrom(i+1,j:j+vars), vars);
elseif ChildTermCnt_2 == 1
% no terms allocated to child 2 yet, so use dummy
% chromosome part consisting of all -1 values
termTest = HasTerm(NewChrom(i,1:ChildTermCnt_1-1), (-1*ones(1,vars+1)), OldChrom(i+1,j:j+vars), vars);
else
termTest = HasTerm(NewChrom(i,1:ChildTermCnt_1-1), NewChrom(i+1,1:ChildTermCnt_2-1), OldChrom(i+1,j:j+vars), vars);
end
newrand = rand(1,1);
if (ChildTermCnt_2 > size(OldChrom,2) && ChildTermCnt_1 > size(OldChrom,2))
error('more terms needed to be allocated, but both polynomials are full, this should not happen')
elseif termTest == 3 || (termTest == 2 && ChildTermCnt_1 > size(OldChrom,2)) || (termTest == 1 && ChildTermCnt_2 > size(OldChrom,2))
% Either term is already in both polys (termTest == 3)
% Or the term is already in poly 2 (termTest == 2), but
% there is no more room in poly 1 (ChildTermCnt_1 >
% size(OldChrom,2)) to add it there
% Or the term is already in poly 1 (termTest == 1), but
% there is no more room in poly 2 (ChildTermCnt_2 >
% size(OldChrom,2)) to add it there
% So we discard the term, and move to the next one
n = n + 1;
elseif (ChildTermCnt_2 > size(OldChrom,2) && ChildTermCnt_1 < size(OldChrom,2)) || termTest == 2 || (termTest == 0 && ChildTermCnt_1 < size(OldChrom,2) && newrand > myRands(i,n))
% If there is no room to append the term to the second
% polynomial, we allocate it to poly 1
% Or if termTest is 2 (i.e. the term already exists in
% the second child polynomial we allocate it to poly 1
% Or if a random number is greater than the previously
% generated random number for this term, we allocate
% it to poly 1
NewChrom(i,ChildTermCnt_1:ChildTermCnt_1+vars) = OldChrom(i+1,j:j+vars);
ChildTermCnt_1 = ChildTermCnt_1 + vars + 1;
n = n + 1;
elseif (ChildTermCnt_1 > size(OldChrom,2) && ChildTermCnt_2 < size(OldChrom,2)) || termTest == 1 || (termTest == 0 && ChildTermCnt_2 < size(OldChrom,2) && newrand <= myRands(i,n))
% If there is no room to append the term to the first
% polynomial, we allocate it to poly 1
% Or if termTest is 2 (i.e. the term already exists in
% the first child polynomial we allocate it to poly 2
% Or if a random number is less than or equal to
% the previously generated random number for this
% term, we allocate it to poly 1
NewChrom(i+1,ChildTermCnt_2:ChildTermCnt_2+vars) = OldChrom(i+1,j:j+vars);
ChildTermCnt_2 = ChildTermCnt_2 + vars + 1;
n = n + 1;
end
end
end
end
end
