This is good to know indeed. Will improve my teaching now, I also did not know this is now done automatically. Thanks for pointing it out.
Jan On Mon, Aug 30, 2021 at 9:44 PM Kay Diederichs < kay.diederi...@uni-konstanz.de> wrote: > Dear Eleanor, > > Thanks for pointing out that CCP4 FreeRflag selects the test set in the > highest possible symmetry for the crystal class! I didn't know that. > > The following sentences (which are somewhat difficult to understand for > me) in https://www.ccp4.ac.uk/html/freerflag.html appear to document that: > "The FreeR_flag is randomly and uniformly distributed > reflexion-by-reflexion, but, additionally, if the keyword NOSYM is not set, > all reflections that are equivalent by the symmetry of the point group of > the twin lattice (assuming the data is twinned), obtain the same flag. This > includes both the possibility of merohedral and pseudomerohedral twinning. > In the latter case, the obliquity parameter can be set using the keyword > OBL." > > I wonder since which CCP4 version (or date) this is the default behaviour. > > best wishes, > Kay > > On Mon, 30 Aug 2021 18:28:23 +0100, Eleanor Dodson < > eleanor.dod...@york.ac.uk> wrote: > > >Back to FreeR factors - Phenix, and I believe FreeRflag now select FreeRs > >in the highest possible symmetry for the crystal class - eh P6/mmm for a > >trigonal crystal, and expand the set to fill the actual space group. This > >means the Free R assignment is suitable if later the crystal symmetry is > >reassigned. But this was not always done in the past so if you are trying > >to reuse free/work assignments from an old project there are possibilities > >of not getting this. Maybe the best solution is to just generate a new > Free > >R set ? > >Eleanor > > > ... > > ######################################################################## > > To unsubscribe from the CCP4BB list, click the following link: > https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 > > This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a > mailing list hosted by www.jiscmail.ac.uk, terms & conditions are > available at https://www.jiscmail.ac.uk/policyandsecurity/ > -- Jan Dohnalek, Ph.D Institute of Biotechnology Academy of Sciences of the Czech Republic Biocev Prumyslova 595 252 50 Vestec near Prague Czech Republic Tel. +420 325 873 758 ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a mailing list hosted by www.jiscmail.ac.uk, terms & conditions are available at https://www.jiscmail.ac.uk/policyandsecurity/
