Cryptic error when importing lmfit

[caenrigen]

With the latest 0.12.0/0.12.1 release we run into a strange issue that seems totally unrelated that depends on the order of the imports of the lmfit and adaptive:

The following fails:

import adaptive  # >=0.12.0
import lmfit
import numpy as np

def cos_func(t, amplitude, frequency, phase, offset):
    """A simple cosine function"""
    return amplitude * np.cos(2 * np.pi * frequency * t + phase) + offset

mod = lmfit.Model(cos_func)
mod.set_param_hint('amplitude', value=1, vary=True)
mod.set_param_hint('frequency', value=0.2)
mod.set_param_hint('phase', value=0, vary=True)
mod.set_param_hint('offset', value=0, vary=False)
params = mod.make_params()
fit_res = mod.fit(np.cos(np.linspace(0, 5, 10)), t=np.linspace(0, 5, 10), params=mod.make_params())

fit_res.plot_fit(show_init=True)

lmfit.model.save_modelresult(fit_res, 'fit_res.json')

throwing

---------------------------------------------------------------------------
KeyError                                  Traceback (most recent call last)
<ipython-input-3-fb6b7cf4fb53> in <module>
     17 fit_res.plot_fit(show_init=True)
     18 
---> 19 lmfit.model.save_modelresult(fit_res, 'fit_res.json')
        global lmfit.model.save_modelresult = <function save_modelresult at 0x12be17830>
        global fit_res = <lmfit.model.ModelResult object at 0x12df5c610>

/usr/local/anaconda3/envs/dclab/lib/python3.7/site-packages/lmfit/model.py in save_modelresult(modelresult=<lmfit.model.ModelResult object>, fname='fit_res.json')
   1258     """
   1259     with open(fname, 'w') as fout:
-> 1260         modelresult.dump(fout)
        modelresult.dump = <bound method ModelResult.dump of <lmfit.model.ModelResult object at 0x12df5c610>>
        fout = <_io.TextIOWrapper name='fit_res.json' mode='w' encoding='UTF-8'>
   1261 
   1262 

/usr/local/anaconda3/envs/dclab/lib/python3.7/site-packages/lmfit/model.py in dump(self=<lmfit.model.ModelResult object>, fp=<_io.TextIOWrapper name='fit_res.json' mode='w' encoding='UTF-8'>, **kws={})
   1668 
   1669         """
-> 1670         return fp.write(self.dumps(**kws))
        fp.write = <built-in method write of _io.TextIOWrapper object at 0x12ae46210>
        self.dumps = <bound method ModelResult.dumps of <lmfit.model.ModelResult object at 0x12df5c610>>
        kws = {}
   1671 
   1672     def loads(self, s, funcdefs=None, **kws):

/usr/local/anaconda3/envs/dclab/lib/python3.7/site-packages/lmfit/model.py in dumps(self=<lmfit.model.ModelResult object>, **kws={})
   1623         out['params'] = [p.__getstate__() for p in self.params.values()]
   1624         out['unique_symbols'] = {key: encode4js(pasteval.symtable[key])
-> 1625                                  for key in pasteval.user_defined_symbols()}
        global key = undefined
        global pasteval.user_defined_symbols = undefined
   1626 
   1627         for attr in ('aborted', 'aic', 'best_values', 'bic', 'chisqr',

/usr/local/anaconda3/envs/dclab/lib/python3.7/site-packages/lmfit/model.py in <dictcomp>(.0=<set_iterator object>)
   1623         out['params'] = [p.__getstate__() for p in self.params.values()]
   1624         out['unique_symbols'] = {key: encode4js(pasteval.symtable[key])
-> 1625                                  for key in pasteval.user_defined_symbols()}
        key = 'wofz'
        global pasteval.user_defined_symbols = undefined
   1626 
   1627         for attr in ('aborted', 'aic', 'best_values', 'bic', 'chisqr',

/usr/local/anaconda3/envs/dclab/lib/python3.7/site-packages/lmfit/jsonutils.py in encode4js(obj=<ufunc 'wofz'>)
     93         else:
     94             val = None
---> 95             importer = find_importer(obj)
        importer = None
        global find_importer = <function find_importer at 0x1083cf170>
        obj = <ufunc 'wofz'>
     96         return dict(__class__='Callable', __name__=obj.__name__,
     97                     pyversion=pyvers, value=val, importer=importer)

/usr/local/anaconda3/envs/dclab/lib/python3.7/site-packages/lmfit/jsonutils.py in find_importer(obj=<ufunc 'wofz'>)
     25         if modname.startswith('__main__'):
     26             continue
---> 27         t = getattr(module, oname, None)
        t = None
        global getattr = undefined
        module = <module 'adaptive.learner.integrator_coeffs' from '/usr/local/anaconda3/envs/dclab/lib/python3.7/site-packages/adaptive/learner/integrator_coeffs.py'>
        oname = 'wofz'
     28         if t is obj:
     29             return modname

/usr/local/anaconda3/envs/dclab/lib/python3.7/site-packages/adaptive/learner/integrator_coeffs.py in __getattr__(attr='wofz')
    188 
    189 def __getattr__(attr):
--> 190     return _coefficients()[attr]
        global _coefficients = <functools._lru_cache_wrapper object at 0x1260d40f0>
        attr = 'wofz'

KeyError: 'wofz'

BUT this seems to work fine:

import lmfit
import adaptive  # >=0.12.0
import numpy as np

def cos_func(t, amplitude, frequency, phase, offset):
    """A simple cosine function"""
    return amplitude * np.cos(2 * np.pi * frequency * t + phase) + offset

mod = lmfit.Model(cos_func)
mod.set_param_hint('amplitude', value=1, vary=True)
mod.set_param_hint('frequency', value=0.2)
mod.set_param_hint('phase', value=0, vary=True)
mod.set_param_hint('offset', value=0, vary=False)
params = mod.make_params()
fit_res = mod.fit(np.cos(np.linspace(0, 5, 10)), t=np.linspace(0, 5, 10), params=mod.make_params())

fit_res.plot_fit(show_init=True)

lmfit.model.save_modelresult(fit_res, 'fit_res.json')

Any idea what is happening? This fails on python 3.7 and also on python 3.8 (on the readthedocs.com)