EXACT_FRAGMENT?

Could someone explain what this does exactly? I found a mention of it in another thread but still can't tell the difference with substructure. It does not seem to be discussed anywhere else, at least the search engine on your front page does not know about it.





Thanks.

Hi,








First, the difference between SUBSTRUCTURE and EXACT search:


SUBSTRUCTURE search finds targets where the query is a subgraph of the target, while EXACT search requires a full graph match.





For example if your query is ethane, exact search will only find ethane, while substructure search will also find bigger structures e.g. propane or cyclohexane.





A single molecule file can contain multiple fragments.


A typical example is a structure displayed with a salt or solvent.


If you use EXACT search, then same salt or solvent must be present in the query as in the target, otherwise there is no match.


To allow ignoring other fragments for EXACT search, we have introduced a new search type.


If you use EXACT_FRAGMENT search, the (one or more) fragments in the query must match with EXACT match in the target, but other fragments may be present, they are ignored.


So this search type behaves as EXACT at fragment level, but as SUBSTRUCTURE for the whole molecule, since additional fragments may be present in the target.





Back to the ethane query (CC) example: The EXACT_FRAGMENT search will only find molecules where at least an ethane fragment is present in the molecule, any additional fragments are allowed. Some match examples for different targets:

Code:

CC                  found CCC                 not found CC.Cl.c1ccccc1      found CCC.Cl              not found CCC.CC              found

Please read our query guide on this search type for more information:





http://www.chemaxon.com/jchem/doc/user/Query.html#otherSearchTypes





Here are some graphical examples of the difference:





http://www.chemaxon.com/jchem/doc/user/QueryMatchExamples.html





I hope I could highlight the difference between these search types for you.





Best regards,





Szilard

Thanks, it makes perfect sense now, except you probably meant to write SUBSTRUCTURE instead of SUPERSTRUCTURE. If that wasn't a typo, then probably I still don't understand.

Quote:

you probably meant to write SUBSTRUCTURE instead of SUPERSTRUCTURE.

Yes, that was a typo indeed.


Thanks for pointing this out, I have fixed it in the text.





Szilard