Dear,
In OB, for a molecule, there is only bit fingerprint out.
How to get the fragments before hashing?
How to get the fragment difference of two molecules?
After get the fragment difference, then how to hash?
Thanks,
Er
I'm not sure what exactly you are after. *There* are general
articles on *fingerprints* and *their* use at:
http://www.daylight.com/dayhtml/doc/*theory*/*theory*.finger.html<http://www.daylight.com/dayhtml/doc/theory/theory.finger.html>
http://www.mesaac.com/*Fingerprint*.htm<http://www.mesaac.com/Fingerprint.htm>
*The* original *OpenBabel* *fingerprint* was written by Fabien
Fontain and is not currently implemented - its concept has
been recoded and extended *in* FP2. Here is his original
description, which mostly applies *to* FP2 as well.
*The* *fingerprint* computation requires *the* execution of *the*
following steps:
- Obtain *the* *fragments*
- Remove duplicate *fragments* and *get* a hash number for
each fragment
- Obtain *the* *fingerprint* of *the* *fragments*
*The* *fragments* are obtained by means of a recursive
algorithm. *The* algorithm finds all linear *fragments* up *to*
a size of seven atoms. Cyclic *fragments* are also
identified by checking if *there* are ring closures *in*
*the* linear fragment. *However*, *the* algorithm does not
identify branched *fragments* if *there* are not part of a ring.
for example CC(C)C will have *the* *fragments*:
C
CC
CCC
and C1C(C)C1 will have *the* *fragments*:
C
CC
CCC
C1CC1
CC1CC1
Duplicate *fragments*, i.e. fragment generated by *the* same
atoms, are removed from *the* fragment list. *The* only
fragment that are kept are *the* ones which produce *the*
lowest hash numbers. *The* hash number for a fragment is an
*integer* number which is generated from *the* atoms and bonds
of *the* fragment. *The* value of this number depends on *the*
position, *the* atomic number and type (aromatic or not) of
*the* atoms of *the* fragment, *the* position and *the* type of
*the* bonds of *the* *fragments*, *the* position and *the* type of
*the* ring closures.
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