Evolutionary algorithm: Difference between revisions

=={{header|Vlang}}==

{{trans|go}}

<lang vlang>import rand

import rand.seed

const target = "METHINKS IT IS LIKE A WEASEL".bytes()

const set = "ABCDEFGHIJKLMNOPQRSTUVWXYZ ".bytes()

fn initialize() []u8 {

rand.seed(seed.time_seed_array(2))

mut parent := []u8{len: target.len}

for i in 0..parent.len {

parent[i] = set[rand.intn(set.len) or {0}]

}

return parent

}

// fitness: 0 is perfect fit. greater numbers indicate worse fit.

fn fitness(a []u8) int {

mut h := 0

// (hamming distance)

for i, tc in target {

if a[i] != tc {

h++

}

}

return h

}

// set m to mutation of p, with each character of p mutated with probability r

fn mutate(p []u8, mut m []u8, r f64) {

for i, ch in p {

if rand.f64() < r {

m[i] = set[rand.intn(set.len) or {0}]

} else {

m[i] = ch

}

}

}

fn main() {

c := 20 // number of times to copy and mutate parent

mut parent := initialize()

mut copies := [][]u8{len: c, init: []u8{len: parent.len}}

println(parent.bytestr())

for best := fitness(parent); best > 0; {

for mut cp in copies {

mutate(parent, mut cp, .05)

}

for cp in copies {

fm := fitness(cp)

if fm < best {

best = fm

parent = cp.clone()

println(parent.bytestr())

}

}

}

}</lang>

{{out}}

<pre>Same as Go entry</pre>