Count The Number Of Times a Value Appears Within an Array

[kevin]

 Count The Number Of Times a Value Appears Within an Array

  This example is really to demo how you the FindArrayCells() function could be used to remove some brute force searching from the PB VM, but not here :).  The demo fills an array of random values (ranged) then counts up the number of times each value appears within the set of data.  To Find each value we're doing a series of linear searches.  You could of course run through and do this manually (shown bellow), but here we're assuming there's some need to use the FIndArrayCells() function.    



 FindArrayCells() Version

PlayBASIC Code: [Select]

   // The range of the values in this array (0-range exclusive)
   NumericRange=10

   // Size of our array to fill with random values   
   Size=10000
   DIm Array(Size)
   

   // Array to hold the tally of each value
   Dim Tally(NumericRange)

Do
   Cls 
   Frames++
      
   
   // Fill this array full of values
   For lp=1 to Size
      Array(lp)=floor(Rnd#(NumericRange))
   next

   // Fill the Tally() array with zeros 
   ClearArray Tally(),0

   t=timer()
   // Run through and count the number of times each value
   // occurs using FindArrayCell()
   For ThisValue=0 to NumericRange-1
      StartPos=1
      repeat
         FoundOffset=FindArrayCell(Array(),StartPos,1,Size,ThisValue)
         if FoundOffset>-1
               STartPos+=FoundOffset+1
               Tally(ThisValue)++   
         endif
      until FoundOffset=-1
   next
   tt#+=timer()-t
   
   print TT#/frames
   
   // Display the 
   Total=0
   For ThisValue=0 to NumericRange-1
         print digits$(ThisValue,2)+" appears "+str$(Tally(ThisValue))+" Times"
      Total+=Tally(ThisValue)
   next

   // 
   print Total      
   Sync
   
   while Spacekey()
   endwhile
 loop   
   

Manual Version

PlayBASIC Code: [Select]

   // The range of the values in this array (0-range exclusive)
   NumericRange=10

   // Size of our array to fill with random values   
   Size=10000
   DIm Array(Size)
   

   // Array to hold the tally of each value
   Dim Tally(NumericRange)

Do
   Cls 
   Frames++
      
   
   // Fill this array full of values
   For lp=1 to Size
      Array(lp)=floor(Rnd#(NumericRange))
   next

   // Fill the Tally() array with zeros 
   ClearArray Tally(),0

   t=timer()
   // Run through and count the number of times each value
   // occurs by hand
   For lp=1 to Size
      ThisValue=Array(lp)
      Tally(ThisValue)++   
   next
   tt#+=timer()-t
   
   print TT#/frames
   
   // Display the 
   Total=0
   For ThisValue=0 to NumericRange-1
         print digits$(ThisValue,2)+" appears "+str$(Tally(ThisValue))+" Times"
      Total+=Tally(ThisValue)
   next

   // 
   print Total      
   Sync
   
   while Spacekey()
   endwhile
 loop   

Manual Search Compared to FindArrayCells()

    This is more of direct 'search' comparison between the two methods, no surprises which one wins this race.  

PlayBASIC Code: [Select]

   // Size of our array to fill with random values   
   Size=100000
   DIm Array(Size)
   

Do
   Cls 
   Frames++
      

   SearchValue=Mod(SearchValue+1,size)
   
   // Fill this array full of values
   if Tick=0
      For lp=1 to Size
         Array(lp)=lp
      next

      // Shuffle the array
      For lp=1 to Size
         Src=rnd(size)
         TEmp=Array(lp)
         Array(lp)=Array(src)
         Array(src)=Temp
      next
   endif
   Tick=Mod(tick+1,10)

   t=timer()
   Index1=0
   // Run through locate this value manually
   For lp=1 to Size
      if SearchValue=Array(lp)
         Index1=lp
         exit
      endif
   next
   tt1#+=timer()-t
   
   print "Average Search Time:"+str$((TT1#/frames)*100)


   t=timer()
   // Use the Find array cell function to brute force search for
   // it
   Index2=1+FindArrayCell(Array(),1,1,Size,SearchValue)   
   tt2#+=timer()-t
   
   print "Average Search Time:"+str$((TT2#/frames)*100)

   if Index1=Index2
      print "Match"

   endif




   Sync
   
   while Spacekey()
   endwhile
 loop