Hi Sean,

On Tue, Nov 1, 2016 at 1:39 PM, Sean Fackler <swfackler@lbl.gov> wrote:

Dear Matt,

I’ve been working to implement Larch functions as a Python library. During the implementation I found a number of things I needed to do including:

You can use Larch functions from Python, of course. Normally, you'd do something like

import larch

from larch_plugins.xafs import pre_edge, mback

1. Identifiying a functions’ python callable name, i.e. _group as a python callable function instead of group as the larch function.

I'm not sure I understand. You shouldn't need "a function's python callable name", you should just need the function. Maybe I misunderstand.

If you need a larch Group, you should be able to do

import larch
agroup = larch.Group(name='mygroupname', xdata = range(100), label='hello')

2. The need to pass '_larch = mylarch’ in the said function or I get the 'AttributeError: 'NoneType' object has no attribute ‘symtable’ ‘

Yes, many of the larch plugin functions either require or are much happier with an instance of a larch session passed in as the '_larch' argument. It's kind of a feature ;).

3. The need to run the script through the Python console as oppose to running as a script.

I'm not sure I understand what this means. You should be able to run a python program from any environment.

You can see my sample script with data attached. Keep in mind I am a Python novice. So for point 3 in particular I don’t understand the difference between running some selected code in the Python console and running the whole script in the shell (I am using PyCharm CE). I checked my Python interpreter with sys.executable (path) and sys.version_info (version) which are the same between the console and interpreter which were initial issues I found online. Is the interpreter somehow not seeing the xraylarch library?

Hmm, that doesn't make a lot of sense to me either. What errors do you get when you run your script?

I don't use PyCharm, so maybe that's not seeing all of the modules from anaconda? Is PyCharm seeing your anaconda distribution?

A few comments on your script:

a) there should be no need to do a os.chdir() to any folder, especially not to source code folders.
b) doing from xxx import * is bound to lead to confusion. Import what you need, and don't import what you don't need.

Finally: 1. Is there an easier way to use the larch functions as a python library?

Is the above suggestion better?

2. Is a larch group basically a python dictionary?

Actually, it's basically an empty class:

    class Group:
        def __init__(self, **kws):
           ....

mygroup = Group()

mygroup.x = 1

mygroup.y = 'a string'

even in more detail, it's an empty class. In most cases it would probably be OK to substitute almost any class instance as a Group.

In Larch, I tend to make as many things as possible "group-like" so that accessing elements is easy.

If so, this could be made clearer in the documentation. I am interested to contribute to the documentation if that’s of interest/help.

Sure! The docs are definitely in need of some serious work.

I am running MacOS Sierra 10.12.1 on a mid-2015 15" MacBook Pro with Python 2.7.

Ron and Alpha: Maybe you have some ideas to the above points?

Thanks everyone for any help.

Sean

The attached modified version of your script works for me from a Terminal (The fit's not very good, yet, but it did run). On Mac OSX with anaconda, you probably have to run this as "pythonw import_fit.py" (note: pythonw, not python).

Hope that helps,

--Matt