On Tue, May 24, 2016 at 11:30 AM, Huebl, Axel <a.huebl@hzdr.de> wrote:
Hi yt-devs,

I am forwarding this conversation to the public list to keep it open for
others to join in and to build up a record that might help others.

Our new student Fabian updated our frontend and implemented particle
readers. Unfortunately some details of the particle "fields" still cause
some bumps that we can not get our head around.

We are now able to read fields and particles, even chunk-wise, and can
work with the data we read in python scripts via the all_data() method.

Nevertheless, using the particle scatter plots such as yt.ParticlePlot
seems not to work. We have some problems with unions / the "all" group
and the fact that we have several particle species (e.g., "hot
electrons", "cold electrons", "helium ions", "nitrogen ions", etc.)

The 'all' particle union should get set up automatically, but maybe something is going wrong with that machinery.

Can you create a test script that illustrates this issue using a publicly available OpenPMD dataset?

Also since the last rebase: did someone recently change the unit system
in yt? T for "Tesla" seems not to be understood any more. Is there a
changelog somewhere available? Do we have to describe our data in cgs / mks?

I just double-checked, and Tesla should be working:

In [1]: from yt import YTQuantity

In [2]: YTQuantity(1, 'T')
Out[2]: 1.0 T

In [3]: YTQuantity(1, 'T').to_equivalent('G', 'CGS')
Out[3]: 10000.0 G
Can you explain a little bit more what issue you're having? A test script that illustrates the issue would also help.

Would someone be interested for a quick heads up via e.g., skype /
web-rtc so we can ask specific questions?

Fabian is around on Tuesdays and Fridays, something like early CA time,
and late GER time usually works great (e.g., 9pm-PDT / 6pm-CEST).

Our current branch HEAD can be found here (->yt->frontends->openPMD):

And an example script is attached.

Thanks a lot!