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Sampling without replacement in jDE #113

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Sampling without replacement in jDE #113

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882193f
Add "Sampling without replacement" function in jde.
neduard Mar 8, 2015
063ea26
Bugfix: the selected (random) elements are at the end of the array.
neduard Mar 8, 2015
2df4b8d
Use "Sampling Without Replacement" algorithm for small populations.
neduard Mar 8, 2015
255ba78
Optimize sampling method in jDE.
neduard Mar 8, 2015
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102 changes: 70 additions & 32 deletions src/algorithm/jde.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -187,40 +187,78 @@ void jde::evolve(population &pop) const
}
}

std::vector<size_t> elements;
if (NP < 21) {
// Add elements in order.
for (size_t i = 0; i < NP; ++i) {
elements.push_back(i);
}
}

//Start of the loop through the deme
for (size_t i = 0; i < NP; ++i) {
do { /* Pick a random population member */
/* Endless loop for NP < 2 !!! */
r1 = p_idx();
} while (r1==i);

do { /* Pick a random population member */
/* Endless loop for NP < 3 !!! */
r2 = p_idx();
} while ((r2==i) || (r2==r1));

do { /* Pick a random population member */
/* Endless loop for NP < 4 !!! */
r3 = p_idx();
} while ((r3==i) || (r3==r1) || (r3==r2));

do { /* Pick a random population member */
/* Endless loop for NP < 5 !!! */
r4 = p_idx();
} while ((r4==i) || (r4==r1) || (r4==r2) || (r4==r3));

do { /* Pick a random population member */
/* Endless loop for NP < 6 !!! */
r5 = p_idx();
} while ((r5==i) || (r5==r1) || (r5==r2) || (r5==r3) || (r5==r4));
do { /* Pick a random population member */
/* Endless loop for NP < 7 !!! */
r6 = p_idx();
} while ((r6==i) || (r6==r1) || (r6==r2) || (r6==r3) || (r6==r4) || (r6==r5));
do { /* Pick a random population member */
/* Endless loop for NP < 8 !!! */
r7 = p_idx();
} while ((r7==i) || (r7==r1) || (r7==r2) || (r7==r3) || (r7==r4) || (r7==r5) || (r7==r6));
if (NP < 21) {
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Currently we include everything in the evolve() method. Would it be a good idea to separate the sampling algorithm (both for small and large NP) into a separate function?

bool i_was_sampled = false;
size_t sampled_i_pos;
// Shuffle 8 elements.
// If 'i' is not picked, then we only use 7 of them.
for (size_t pos = 0; pos < 8; ++pos) {
// uniform_int<> rnd(a,b) gives values in the range [a,b] not [a,b).
boost::uniform_int<size_t> rnd_idx(0, NP - pos - 1);
size_t rnd = rnd_idx(m_urng);
if (elements[rnd] == i) {
i_was_sampled = true;
// Remember where we put i.
sampled_i_pos = NP - pos - 1;
}
std::swap(elements[rnd], elements[NP - pos - 1]);
}

if (i_was_sampled) {
std::swap(elements[sampled_i_pos], elements[NP - 7 - 1]);
}

r1 = elements[NP - 1];
r2 = elements[NP - 2];
r3 = elements[NP - 3];
r4 = elements[NP - 4];
r5 = elements[NP - 5];
r6 = elements[NP - 6];
r7 = elements[NP - 7];
} else {
do { /* Pick a random population member */
/* Endless loop for NP < 2 !!! */
r1 = p_idx();
} while (r1==i);

do { /* Pick a random population member */
/* Endless loop for NP < 3 !!! */
r2 = p_idx();
} while ((r2==i) || (r2==r1));

do { /* Pick a random population member */
/* Endless loop for NP < 4 !!! */
r3 = p_idx();
} while ((r3==i) || (r3==r1) || (r3==r2));

do { /* Pick a random population member */
/* Endless loop for NP < 5 !!! */
r4 = p_idx();
} while ((r4==i) || (r4==r1) || (r4==r2) || (r4==r3));

do { /* Pick a random population member */
/* Endless loop for NP < 6 !!! */
r5 = p_idx();
} while ((r5==i) || (r5==r1) || (r5==r2) || (r5==r3) || (r5==r4));
do { /* Pick a random population member */
/* Endless loop for NP < 7 !!! */
r6 = p_idx();
} while ((r6==i) || (r6==r1) || (r6==r2) || (r6==r3) || (r6==r4) || (r6==r5));
do { /* Pick a random population member */
/* Endless loop for NP < 8 !!! */
r7 = p_idx();
} while ((r7==i) || (r7==r1) || (r7==r2) || (r7==r3) || (r7==r4) || (r7==r5) || (r7==r6));
}

// Adapt amplification factor and crossover probability
double F=0, CR=0;
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