Re: [Rdkit-discuss] beta of Q2 release available

[Greg L. <gre...@gm...>]

On Sun, Jun 21, 2009 at 10:24 AM, Evgueni Kolossov<eko...@gm...> wrote:
>
> Can you please explain the usage of atom labels Q, A, and *. I know that *
> used in fragments. Where you using Q and A?
>

My interpretation of these is:
* : a query matching any atom
A : a query matching anything but H
Q : a query matching anything but C or H

Note that molecules processed by the RDKit don't normally contain Hs,
so the "H" bits of the queries above don't really do anything and a
'*' doesn't match where it ought to. For example, a Mol file query
with a C connected to a * should match methane. Using the RDKit it
normally will not (since the Hs are not present in the graph and
molecules normally have had Hs removed). This is something that ought
to be fixed at some point in the future.

-greg