Data update

Task/Evolutionary-algorithm/FutureBasic/evolutionary-algorithm.basic

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+include "NSLog.incl"
+
+begin globals
+  CFStringRef target
+  CFStringRef alphabet
+  NSInteger   c
+  CGFloat     p
+end globals
+
+target   = @"METHINKS IT IS LIKE A WEASEL"
+alphabet = @"ABCDEFGHIJKLMNOPQRSTUVWXYZ "
+c = 100
+p = 0.06
+
+toolbox fn arc4random_uniform( UInt32 upperbound ) = UInt32
+
+local fn Fitness( s as CFStringRef ) as NSInteger
+  NSInteger score = len(target)
+  for NSInteger i = 0 to len(target) -1
+    if ( ucc(s,i) == ucc(target,i) ) then score--
+  next
+end fn = score
+
+local fn Mutate( s as CFStringRef, rate as CGFloat ) as CFStringRef
+  CFMutableStringRef result = fn MutableStringWithString( @"" )
+  for NSInteger i = 0 to len(s) -1
+    if ( ( fn arc4random_uniform(100) / 100.0) < rate )
+      NSInteger idx = fn arc4random_uniform( (UInt32)len(alphabet) )
+      MutableStringAppendFormat( result, @"%C", ucc( alphabet, idx ) )
+    else
+      MutableStringAppendFormat( result, @"%C", ucc( s, i ) )
+    end if
+  next
+end fn = result
+
+local fn RandomString( length as NSInteger ) as CFStringRef
+  CFMutableStringRef result = fn MutableStringWithString( @"" )
+  for NSInteger i = 0 to length -1
+    NSInteger idx = fn arc4random_uniform( (UInt32)len(alphabet) )
+    MutableStringAppendFormat( result, @"%C", ucc( alphabet, idx ) )
+  next
+end fn = result
+
+void local fn PrintStep( stepNum as NSInteger, s as CFStringRef, fit as NSInteger, result as CFMutableStringRef )
+  MutableStringAppendFormat( result, @"%3ld: %@  Distance: %ld\n", (long)stepNum, s, (long)fit )
+end fn
+
+local fn EvolveString as CFStringRef
+  CFMutableStringRef result = fn MutableStringNew
+  CFStringRef parent = fn RandomString( len(target) )
+  fn PrintStep( 0, parent, fn Fitness(parent), result )
+
+  NSInteger stepNum = 0
+  while ( fn StringIsEqual( parent, target ) == NO )
+    NSInteger   bestFitness = len(target) + 1
+    CFStringRef bestChild = @""
+    CFStringRef child
+    NSInteger   fit
+
+    for NSInteger i = 0 to c -1
+      child = fn Mutate( parent, p )
+      fit = fn Fitness( child )
+      if ( fit < bestFitness )
+        bestFitness = fit
+        bestChild = child
+      end if
+    next
+    parent = bestChild
+    stepNum++
+    fn PrintStep( stepNum, parent, bestFitness, result )
+  wend
+end fn = result
+
+CFTimeInterval t : t = fn CACurrentMediaTime
+CFStringRef result : result = fn EvolveString
+NSLog( @"\nCompute time: %.3f ms\n",(fn CACurrentMediaTime-t)*1000 )
+NSLog( @"%@", result )
+NSLogScrollToTop
+
+HandleEvents