This commit is contained in:
Ingy döt Net 2013-04-10 21:29:02 -07:00
parent 764da6cbbb
commit db842d013d
19005 changed files with 197040 additions and 7 deletions

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class Main
{
static const Str target := "METHINKS IT IS LIKE A WEASEL"
static const Int C := 100 // size of population
static const Float p := 0.1f // chance any char is mutated
// compute distance of str from target
static Int fitness (Str str)
{
Int sum := 0
str.each |Int c, Int index|
{
if (c != target[index]) sum += 1
}
return sum
}
// mutate given parent string
static Str mutate (Str str)
{
Str result := ""
str.size.times |Int index|
{
result += ((Float.random < p) ? randomChar() : str[index]).toChar
}
return result
}
// return a random char
static Int randomChar ()
{
"ABCDEFGHIJKLMNOPQRSTUVWXYZ "[Int.random(0..26)]
}
// make population by mutating parent and sorting by fitness
static Str[] makePopulation (Str parent)
{
Str[] result := [,]
C.times { result.add (mutate(parent)) }
result.sort |Str a, Str b -> Int| { fitness(a) <=> fitness(b) }
return result
}
public static Void main ()
{
Str parent := ""
target.size.times { parent += randomChar().toChar }
while (parent != target)
{
echo (parent)
parent = makePopulation(parent).first
}
echo (parent)
}
}

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global target, chars, parent, C, M, current_fitness
procedure fitness(s)
fit := 0
#Increment the fitness for every position in the string s that matches the target
every i := 1 to *target & s[i] == target[i] do fit +:= 1
return fit
end
procedure mutate(s)
#If a random number between 0 and 1 is inside the bounds of mutation randomly alter a character in the string
if (?0 <= M) then ?s := ?chars
return s
end
procedure generation()
population := [ ]
next_parent := ""
next_fitness := -1
#Create the next population
every 1 to C do push(population, mutate(parent))
#Find the member of the population with highest fitness, or use the last one inspected
every x := !population & (xf := fitness(x)) > next_fitness do {
next_parent := x
next_fitness := xf
}
parent := next_parent
return next_fitness
end
procedure main()
target := "METHINKS IT IS LIKE A WEASEL" #Our target string
chars := &ucase ++ " " #Set of usable characters
parent := "" & every 1 to *target do parent ||:= ?chars #The universal common ancestor!
current_fitness := fitness(parent) #The best fitness we have so far
C := 50 #Population size in each generation
M := 0.5 #Mutation rate per individual in a generation
gen := 1
#Until current fitness reaches a score of perfect match with the target string keep generating new populations
until ((current_fitness := generation()) = *target) do {
write(gen || " " || current_fitness || " " || parent)
gen +:= 1
}
write("At generation " || gen || " we found a string with perfect fitness at " || current_fitness || " reading: " || parent)
end

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CHARSET=: 'ABCDEFGHIJKLMNOPQRSTUVWXYZ '
NPROG=: 100 NB. number of progeny (C)
MRATE=: 0.05 NB. mutation rate
create =: (?@$&$ { ])&CHARSET NB. creates random list from charset of same shape as y
fitness =: +/@:~:"1
copy =: # ,:
mutate =: &(>: $ ?@$ 0:)(`(,: create))} NB. adverb
select =: ] {~ (i. <./)@:fitness NB. select fittest member of population
nextgen =: select ] , [: MRATE mutate NPROG copy ]
while =: conjunction def '(] , (u {:))^:(v {:)^:_ ,:'
evolve=: nextgen while (0 < fitness) create

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filter=: {: ,~ ({~ i.@>.&.(%&20)@#) NB. take every 20th and last item
filter evolve 'METHINKS IT IS LIKE A WEASEL'
XXURVQXKQXDLCGFVICCUA NUQPND
MEFHINVQQXT IW LIKEUA WEAPEL
METHINVS IT IW LIKEUA WEAPEL
METHINKS IT IS LIKE A WEASEL

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CHARSET=: 'ABCDEFGHIJKLMNOPQRSTUVWXYZ '
NPROG=: 100 NB. "C" from specification
fitness=: +/@:~:"1
select=: ] {~ (i. <./)@:fitness NB. select fittest member of population
populate=: (?@$&# { ])&CHARSET NB. get random list from charset of same length as y
log=: [: smoutput [: ;:inv (('#';'fitness: ';'; ') ,&.> ":&.>)
mutate=: dyad define
idxmut=. I. x >: (*/$y) ?@$ 0
(populate idxmut) idxmut"_} y
)
evolve=: monad define
target=. y
parent=. populate y
iter=. 0
mrate=. %#y
while. 0 < val=. target fitness parent do.
if. 0 = 50|iter do. log iter;val;parent end.
iter=. iter + 1
progeny=. mrate mutate NPROG # ,: parent NB. create progeny by mutating parent copies
parent=. target select parent,progeny NB. select fittest parent for next generation
end.
log iter;val;parent
parent
)

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evolve 'METHINKS IT IS LIKE A WEASEL'
#0 fitness: 27 ; YGFDJFTBEDB FAIJJGMFKDPYELOA
#50 fitness: 2 ; MEVHINKS IT IS LIKE ADWEASEL
#76 fitness: 0 ; METHINKS IT IS LIKE A WEASEL
METHINKS IT IS LIKE A WEASEL

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C = 10
'mutaterate has to be greater than 1 or it will not mutate
mutaterate = 2
mutationstaken = 0
generations = 0
Dim parentcopies$((C - 1))
Global targetString$ : targetString$ = "METHINKS IT IS LIKE A WEASEL"
Global allowableCharacters$ : allowableCharacters$ = " ABCDEFGHIJKLMNOPQRSTUVWXYZ"
currentminFitness = Len(targetString$)
For i = 1 To Len(targetString$)
parent$ = parent$ + Mid$(allowableCharacters$, Int(Rnd(1) * Len(allowableCharacters$)), 1)
Next i
Print "Parent = " + parent$
While parent$ <> targetString$
generations = (generations + 1)
For i = 0 To (C - 1)
parentcopies$(i) = mutate$(parent$, mutaterate)
mutationstaken = (mutationstaken + 1)
Next i
For i = 0 To (C - 1)
currentFitness = Fitness(targetString$, parentcopies$(i))
If currentFitness = 0 Then
parent$ = parentcopies$(i)
Exit For
Else
If currentFitness < currentminFitness Then
currentminFitness = currentFitness
parent$ = parentcopies$(i)
End If
End If
Next i
CLS
Print "Generation - " + str$(generations)
Print "Parent - " + parent$
Scan
Wend
Print
Print "Congratulations to me; I finished!"
Print "Final Mutation: " + parent$
'The ((i + 1) - (C)) reduces the total number of mutations that it took by one generation
'minus the perfect child mutation since any after that would not have been required.
Print "Total Mutations Taken - " + str$(mutationstaken - ((i + 1) - (C)))
Print "Total Generations Taken - " + str$(generations)
Print "Child Number " + str$(i) + " has perfect similarities to your target."
End
Function mutate$(mutate$, mutaterate)
If (Rnd(1) * mutaterate) > 1 Then
'The mutatingcharater randomizer needs 1 more than the length of the string
'otherwise it will likely take forever to get exactly that as a random number
mutatingcharacter = Int(Rnd(1) * (Len(targetString$) + 1))
mutate$ = Left$(mutate$, (mutatingcharacter - 1)) + Mid$(allowableCharacters$, Int(Rnd(1) * Len(allowableCharacters$)), 1) _
+ Mid$(mutate$, (mutatingcharacter + 1))
End If
End Function
Function Fitness(parent$, offspring$)
For i = 1 To Len(targetString$)
If Mid$(parent$, i, 1) <> Mid$(offspring$, i, 1) Then
Fitness = (Fitness + 1)
End If
Next i
End Function

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make "target "|METHINKS IT IS LIKE A WEASEL|
to distance :w
output reduce "sum (map.se [ifelse equal? ?1 ?2 [0][1]] :w :target)
end
to random.letter
output pick "| ABCDEFGHIJKLMNOPQRSTUVWXYZ|
end
to mutate :parent :rate
output map [ifelse random 100 < :rate [random.letter] [?]] :parent
end
make "C 100
make "mutate.rate 10 ; percent
to breed :parent
make "parent.distance distance :parent
localmake "best.child :parent
repeat :C [
localmake "child mutate :parent :mutate.rate
localmake "child.distance distance :child
if greater? :parent.distance :child.distance [
make "parent.distance :child.distance
make "best.child :child
]
]
output :best.child
end
to progress
output (sentence :trials :parent "distance: :parent.distance)
end
to evolve
make "parent cascade count :target [lput random.letter ?] "||
make "trials 0
while [not equal? :parent :target] [
make "parent breed :parent
print progress
make "trials :trials + 1
]
end

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target = "METHINKS IT IS LIKE A WEASEL";
alphabet = CharacterRange["A", "Z"]~Join~{" "};
fitness = HammingDistance[target, #] &;
Mutate[parent_String, rate_: 0.01, fertility_Integer: 25] := Module[
{offspring, kidfits, gen = 0, alphabet = CharacterRange["A", "Z"]~Join~{" "}},
offspring = ConstantArray[Characters[parent], fertility];
Table[
If[RandomReal[] <= rate, offspring[[j, k]] = RandomChoice[alphabet]],
{j, fertility}, {k, StringLength@parent}
];
offspring = StringJoin[#] & /@ offspring;
kidfits = fitness[#] & /@ Flatten[{offspring, parent}];
Return[offspring[[First@Ordering[kidfits]]]];
];
mutationRate = 0.02;
parent = StringJoin[ alphabet[[RandomInteger[{1, Length@alphabet}, StringLength@target]]] ];
results = NestWhileList[Mutate[#, mutationRate, 100] &, parent, fitness[#] > 0 &];
fits = fitness[#] & /@ results;
results = Transpose[{results, fits}];
TableForm[results[[;; ;; 2]], TableHeadings->{Range[1, Length@results, 2],{"String","Fitness"}}, TableSpacing -> {1, 2}]