From: broersma.juda_ANTISPAM_@tiscali.nl   
      
   Op Sun, 9 Oct 2005 22:49:21 +0100 schreef Dr John Stockton   
      
   >>function CodonHash(const ACodon: tCodon): Longint;   
   >>begin   
   >>  Result := (Ord(ACodon[1]) shl 16) + (Ord(ACodon[2]) shl 8) +   
   >>Ord(ACodon[3]);   
   >>end;   
   >   
   [snip]   
   >It looks like Delphi; I don't recall Return in Pascal.   
   Yep, I recoded it in Delphi, my TP6 won't run under WinME on my   
   machine...   
      
   >This should be   
   >quicker, and gives the same but with a leading 3.   
   >   
   >        function CodonHash(const ACodon: tCodon): Longint;   
   >        begin CodonHash := Longint(ACodon) end;   
   Tried that: it gives me a compile error: invalid typecast   
   Tried move(ACodon,Result,3) --> gives same result (as expected) but is   
   slower.   
      
      
   >Or, since the codons are made of ACGU only, encode each letter as 2 bits   
   >and store in a byte; you can then look the translation up in a small   
   >array of enumerated or string (fill unused entries with 0 or '').   
   Gonna give that a try   
      
      
   >Since a letter needs only 5 bits, you could try encoding three in a byte   
   >as (X1*2+X2)*2+X3; there *may* be no duplicates.  In fact, only 3 bits   
   >vary in ACGU : ...X.XX. : so (X1*32+X2)*32+X3 looks safe, using word   
   >arithmetic.   
   Will try that too   
      
      
   >Arrange your numbers in order, and use a binary search; for 64 entries,   
   >that's about 6 comparisons rather than average 32.   
   My nested case scenario probably requires less comparisons on average,   
   so maybe its hard to get faster?   
      
   Bart   
   --   
   Bart Broersma   
   broersma.juda_ANTISPAM_@tiscali.nl   
   (ff _ANTISPAM_ wegpoetsen uit dit adres natuurlijk)   
      
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