frame_sum and frame_average

[ambarb]

• need both because people are doing one or both

• units:

• [x] NX: @prjemian put in NX issue for this - need to resolve first. Pete decides.

• [x] pint: has counts and counts per second

• required: optional for both

• [x] do we need a label (unit label attribute) -- this will be NX_COUNT

[prjemian]

follow: https://github.com/nexusformat/definitions/issues/932

[prjemian]

NeXus intends to add NX_COUNT (singular) to the list of unit types.

[JulReinhardt]

So will we not simply use "counts" as unit here?

[prjemian]

We can continue to use units="counts" here as I believe NeXus will approve the addition of NX_COUNTS as a units type. The pint package recognizes "counts" as a kind of units.

The NeXus issue (https://github.com/nexusformat/definitions/issues/932) is scheduled for consideration at the next NIAC meeting (Sept or Oct this year). This issue was discussed at the NeXus teleconference this week (2021-07-28).

[ambarb]

@prjemian updated us on this state of things in the NX community - they are willing to consider, but the preferences is based on real use cases , like ours.

for our case, do we want to require a label?
@ambarb find out what XPCS community wants (counts, counts per second) for average or sum list.

[JulReinhardt]

Note: currently frame_sum and frame_average are of units NX_ANY same for g2 and and two_time_corr_func. What's the latest decision?

Apart from that this issue is ready to be closed (automatically) once PR is approved.

[ambarb]

these probably should be total counts but we have no way of know if someone decides to divide by exposure time to get "per sec" to understand the count rate. Could we include a note that ideally it seems "counts" would be the best unit of measurement, but we are not stopping people from per sec or even using ADU?

[ambarb]

also note, some related discussion in #63 for a full picture.

[ambarb]

I will find out what the community wants in the meantime, but I think no one is going to want to force units. Sending email out now.

[prjemian]

Could we include a note that ideally it seems "counts" would be the best unit of measurement

This is good content for the documentation.

[ambarb]

units will be NX_COUNT and pretend that it is a standard definition in NX so once this unit label attribute is added here(to our current PR), we can move this to complete.

[prjemian]

This is part of PR#52.