ValueError loading data for scipy.odr regression

Question

I recently tried to use scipy.odr package to conduct a regression analysis. Whenever I try to load a list of data where the elements depend on a function, a value error is raised:

ValueError: x could not be made into a suitable array

I have been using the same kind of programming to make fits using scipy's leastsq and curve_fit routines without problems.

Any idea of what to change and how to proceed? Thanks a lot...

Here I include a minimal working example:

from scipy import odr
from functools import partial
import numpy as np
import matplotlib.pyplot as plt

### choose select=0 and for myModel a list of elements is called which are a function of some parameters
### this results in error message: ValueError: x could not be made into a suitable array
### choose select=1, the function temp is exlcuded, and a fit is generated
### what do i have to do in order to run the programm successfully using select=0? 

## choose here!
select=1

pfit=[1.0,1.0]
q0=[1,2,3,4,5]
q1=[3,8,10,19,27]


def temp(par, val):
    p1,p2=par       
    temp_out = p1*val**p2
    return temp_out

def fodr(a,x):
    if select==0:
        fitf = np.array([xi(a) for xi in x])
    else:          
        fitf= a[0]*x**a[1]
    return fitf

# define model
myModel = odr.Model(fodr)
# load data
damy=q1
if select==0:
    damx=[]
    for el in q0:
        elm=partial(temp,val=el)
        damx.append(elm)
    #damx=[el(pfit) for el in damx]  # check that function temp works fine
    #print damx
else:   
    damx=q0

myData = odr.Data(damx, damy)   
myOdr = odr.ODR(myData, myModel , beta0=pfit, maxit=100, ifixb=[1,1])   
out = myOdr.run()
out.pprint()

Edit:

@ Robert: Thanks for your reply. I am using scipy version '0.14.0'. Using select==0 in my minimal example I get following traceback:

Traceback (most recent call last):
File "scipy-odr.py", line 48, in <module>
out = myOdr.run()
File "/home/tg/anaconda/lib/python2.7/site-packages/scipy/odr/odrpack.py", line 1061, in run
self.output = Output(odr(*args, **kwds))
ValueError: x could not be made into a suitable array

Answer 1

In short, your code does not work because damx is a now a list of functools.partial .

scipy.odr is a simple wrapper around Fortran Orthogonal Distance Regression ( ODRPACK ), both xdata and ydata have to be numerical since they will be converted to some Fortran type under the hood. It doesn't know what to do with a list of functools.partial , therefore the error.