Re: [Open Babel] how to know the corresponding substructure of each bit in fingerprint

[Craig A. J. <cj...@em...>]

Chris Morley wrote:
>>> Another question is whether the mean of each bit is fixed or changed
>>> according to the input molecules.
>> I think you're asking, "the meaning", that is, what each bit represents.  The answer is no, the meaning of each bit does not ever change, no matter what molecule is input.  However, there is no way to know what each bit means since a hash is used.
>>
> The default fingerprint in OpenBabel, "FP2", is of this Daylight type as 
> above.
> 
> "FP4" is of a different type. Each bit represents a chemical feature 
> defined by a set of 307 SMARTS patterns...

Ok, I know this is a quibble, but... 

Strictly speaking, shouldn't these be called "structural keys" rather than "fingerprints"?  Even though FP4 uses OB's fingerprint object, it really should be called something like "SK4".  (I suppose the fingerprint object should have a more generic name like "BitVector".  Not that we should change the C++ class names.)  Many people are introduced to cheminformatics through OpenBabel, and correct terminology can be very helpful.

Craig