mailRe: Add the userfunction relax_disp.select_SN_ratio for the possibility to deselect spins, with a certain signal/noise ratio


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Posted by Troels Emtekær Linnet on December 05, 2014 - 17:43:
Hi Edward.

That is a very good question for selection.

If any or all is below S/N Threshold.

Hm.
I would have to think about that.

I think I will just start by calculating it.

Best
Troels


2014-12-05 16:51 GMT+01:00 Edward d'Auvergne <edward@xxxxxxxxxxxxx>:

Hi Troels,

That's a good idea, feel free to implement it.  I would suggest coming
up with a different user function name though, as this is 100%
independent of the relaxation dispersion analysis.  It might fit
better in the spectrum user function class
(spectrum.deselect_sn_ratio).  Or maybe even better, the select and
deselect user function classes (select.sn_ratio, deselect.sn_ratio).
For consistency, it would be better to use all lower case.    I would
also suggest creating the spectrum.sn_ratio user function to
pre-calculate the S/N ratio, as this could have other uses.  It could
be stored in spin.sn_ratio as a dictionary with the same keys as
spin.intensity and spin.intensity_err.

How would this be implemented though?  Would you look at all peak
intensities for a spin divided by the intensity error and deselect if
any is below?  Or if all are below?

Regards,

Edward





On 5 December 2014 at 16:25, Troels Emtekær Linnet
<tlinnet@xxxxxxxxxxxxx> wrote:
Hi Edward.

Would it be useful to add additional features on top of the
relax_disp.insignificant function?

A possibility to only select spins, which have a S/N above 10 or more?

This could be run before analysis, and only depends
on spectrum.error_analysis().

The relax_disp.insignificant function is not enough.

If a "weak" peak is loaded, with intensity near the noise, then
calculation
of R2eff can fluctuate quite a bit.
This will not be observable with relax_disp.insignificant.

The SN ratio could even be calculated and stored when doing the
spectrum.error_analysis().

Best
Troels
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