[Ifeffit] Larch user base?

[Matt Newville]

Hi Sean,

On Sun, Aug 14, 2016 at 4:35 PM, Sean Fackler <swfackler at lbl.gov> wrote:

> Hello all!
>
> Do you have an idea of Larch user base or Larch package download stats?
> Thanks for any information.
>
>
Funny you should ask.   It turns out that a kind and generous NSF Program
Manager recently gave me a friendly reminder that I promised to include
such information in a report to them.   I think I haven't been doing enough
to promote or discuss development of Larch, so while we're at it, I should
probably give an update on the status of Larch and where it looks to be
going over the next couple years.

First, your question:

The recommended way to download / install Larch in now via Anaconda.org:
https://anaconda.org/newville/xraylarch, which conveniently keeps
statistics. This reports more than 180 downloads in 2016.  That's low
compared to Athena/Artemis, but not terrible.  Many of these are probably
from users of my beamline, where Larch includes the Visualization tools for
the XRF maps we make, but then again, this was a major motivation for Larch.

For another metric, I counted about 1 discussion per month on this list
about Larch.   There are at least that many discussions where Bruce or I
eventually say "what you're asking would be much easier with Larch".
While low compared to questions about using Demeter many of the Demeter
questions posed don't really discuss the underlying analysis engine.

Anecdotally, I've had many discussions over the past year about Larch,
including getting "advanced" Athena/Artemis users and beamline scientists
to use it.   The conversations always seem positive to me, but I don't know
that many people have really taken it up from these discussions. I've also
had several discussions with people (beamline scientists or visiting
scientists) at the APS in a similar manner -- many seem interested, but I'm
not sure the adoption rate is very high.  There are definitely a handful of
folks trying to use it from Python.

Athena and Artemis can already use Larch, and I think both Bruce and I are
expecting that Larch will be expected to be the default over the next
year.

Larch status and near-term directions:

I'm about to merge a large set of changes (https://github.com/xraypy/
xraylarch/pull/139) and push a new release of Larch (0.9.30), probably
later this week.  The main changes / updates for this release are:
    1. initial support for Python 3.  All the basic stuff is working, but
there may still be some small problems with unicode vs. strings, and with
the wxPython GUIs
    2. support for wxPhoenix, the not-yet-officially-released version of
wxPython that will support Python 3. Again, there may be a few problems
still to uncover, but stuff is mostly working for me with wxPhoenix on
wxPython.
    3. improvements and simplifications to the internal "read-eval-print"
loop code (some of the oldest code in larch) and to the presentation of
exceptions / error messages.
    4. A reader for Athena project files to Larch groups.  A writer will
soon follow, I expect.

As mentioned, we have funding and have hired a scientist to work on parts
of Larch.  This is to integrate and/or improve 4 aspects:
   1. handling micro-XRD data, and automating phase ID from micro-XRD maps.
   2. better fitting / quantitative XRF analysis.
   3. better XANES fitting and linear analysis methods (PCA, and more).
   4. improved EXAFS analysis, incorporating dedicated Feff85EXAFS.

We think we know how to do all of these steps, but we'd love help with any
part of this.   The person we've hired is tackling #1 first,  For my part,
I'll be working on #3, and a dedicated GUI for XANES analysis over the next
several months.

There are several related projects (mostly python), including
https://github.com/xraypy/feff85exafs, https://github.com/scikit-beam/,
https://github.com/lmfit/lmfit-py.   LMFIT grew out of Larch, but has grown
substantially from outside collaborators. I expect that part of the XANES
and XRF fitting work will migrate Larch's fitting to just depend on LMFIT.
  It's possible that some of the domain-specific libraries for analysis
(Xray databases, for example at https://github.com/scikit-beam/XrayDB) will
migrate to scikit-beam, with Larch then depending on that.

Larch is definitely ready to be used.  Many aspects are still in
development, but the core EXAFS analysis is working.  If you or anyone is
interested in trying it or working with the code, don't hesitate to give it
a try.

Sorry for such a long answer to a short question!

--Matt
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