[cctbxbb] Asymmetric Unit with cctbx

[Philipp Heuser]

Thanks for your replies. I found a way to evaluate the informations 
given by the direct_space_asu().facets. This is rather slow, but since I 
am doing some prototyping at the moment I don't care about speed to much 
right now. Thanks again!

Regards
Philipp


Ralf W. Grosse-Kunstleve schrieb:
> Hi Phillip,
>
> Could you give a brief overview of what you want to do?
> There are many ways of handling the contiguous asu information, but
> how much effort a particular approach is worth highly depends on
> the application. E.g. it is important to understand how important
> runtime performance is vs. memory use vs. developer time.
> Note that the contiguous asymmetric units are fully defined in the
> cctbx.sgtbx.direct_space_asu module (this is behind the asu gallery
> Peter pointed out). However, the full information for handling all
> conditions on the facets, edges and vertices is only available in
> Python. For processing maps this is likely to be too slow, unless you
> really don't care about runtime.
> In C++, the contiguous asymmetric units are only used as
> volumes: cctbx/crystal/direct_space_asu.h, classes float_cut_plane
> and float_asu, which duplicate some of the Python code. It is not
> a severe duplication since the facet/edge/vertex conditions are
> meaningless when working with floating-point numbers and can therefore
> be dropped. When dealing with grid points in maps you need those
> conditions somehow, either from some sort of reference table as
> we have in Python, or by looping over the symmetry operations.
> Handling the full conditions in C++ would be quite a bit of work,
> I think. It would be cool to have in general, but so far I didn't
> have an application important enough to justify the effort.
>
> Ralf
>
>
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-- 

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Dr Philipp Heuser
Postdoctoral fellow

EMBL-Hamburg 
c/o Building 25A, DESY
Notkestrasse 85
22603 Hamburg

phone:   +49 40 89902 188
fax:     +49 40 89902 149
mail:    philipp.heuser at embl-hamburg.de
web:     www.philipp-heuser.de

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