Help on error " ValueError: For numerical factors, num_columns must be an int "

[Robert]

On Wednesday, December 16, 2015 at 6:34:21 AM UTC-5, Mark Lawrence wrote:
> On 16/12/2015 10:44, Robert wrote:
> > Hi,
> >
> > When I run the following code, there is an error:
> >
> > ValueError: For numerical factors, num_columns must be an int
> >
> >
> > ================
> > import numpy as np
> > import pandas as pd
> > from patsy import dmatrices
> > from sklearn.linear_model import LogisticRegression
> >
> > X = [0.5,0.75,1.0,1.25,1.5,1.75,1.75,2.0,2.25,2.5,2.75,3.0,3.25,
> > 3.5,4.0,4.25,4.5,4.75,5.0,5.5]
> > y = [0,0,0,0,0,0,1,0,1,0,1,0,1,0,1,1,1,1,1,1]
> >
> > zipped = list(zip(X,y))
> > df = pd.DataFrame(zipped,columns = ['study_hrs','p_or_f'])
> >
> > y, X = dmatrices('p_or_f ~ study_hrs', df, return_type="dataframe")
> > =======================
> >
> > I have check 'df' is this type:
> > =============
> > type(df)
> > Out[25]: pandas.core.frame.DataFrame
> > =============
> >
> > I cannot figure out where the problem is. Can you help me?
> > Thanks.
> >
> > Error message:
> > ..........
> >
> >
> > ---------------------------------------------------------------------------
> > ValueError                                Traceback (most recent call last)
> > C:\Users\rj\pyprj\stackoverflow_logisticregression0.py in <module>()
> >       17 df = pd.DataFrame(zipped,columns = ['study_hrs','p_or_f'])
> >       18
> > ---> 19 y, X = dmatrices('p_or_f ~ study_hrs', df, return_type="dataframe")
> >       20
> >       21 y = np.ravel(y)
> >
> > C:\Users\rj\AppData\Local\Enthought\Canopy\User\lib\site-packages\patsy\highlevel.pyc in dmatrices(formula_like, data, eval_env, NA_action, return_type)
> >      295     eval_env = EvalEnvironment.capture(eval_env, reference=1)
> >      296     (lhs, rhs) = _do_highlevel_design(formula_like, data, eval_env,
> > --> 297                                       NA_action, return_type)
> >      298     if lhs.shape[1] == 0:
> >      299         raise PatsyError("model is missing required outcome variables")
> >
> > C:\Users\rj\AppData\Local\Enthought\Canopy\User\lib\site-packages\patsy\highlevel.pyc in _do_highlevel_design(formula_like, data, eval_env, NA_action, return_type)
> >      150         return iter([data])
> >      151     design_infos = _try_incr_builders(formula_like, data_iter_maker, eval_env,
> > --> 152                                       NA_action)
> >      153     if design_infos is not None:
> >      154         return build_design_matrices(design_infos, data,
> >
> > C:\Users\rj\AppData\Local\Enthought\Canopy\User\lib\site-packages\patsy\highlevel.pyc in _try_incr_builders(formula_like, data_iter_maker, eval_env, NA_action)
> >       55                                       data_iter_maker,
> >       56                                       eval_env,
> > ---> 57                                       NA_action)
> >       58     else:
> >       59         return None
> >
> > C:\Users\rj\AppData\Local\Enthought\Canopy\User\lib\site-packages\patsy\build.pyc in design_matrix_builders(termlists, data_iter_maker, eval_env, NA_action)
> >      704                             factor_states[factor],
> >      705                             num_columns=num_column_counts[factor],
> > --> 706                             categories=None)
> >      707         else:
> >      708             assert factor in cat_levels_contrasts
> >
> > C:\Users\rj\AppData\Local\Enthought\Canopy\User\lib\site-packages\patsy\design_info.pyc in __init__(self, factor, type, state, num_columns, categories)
> >       86         if self.type == "numerical":
> >       87             if not isinstance(num_columns, int):
> > ---> 88                 raise ValueError("For numerical factors, num_columns "
> >       89                                  "must be an int")
> >       90             if categories is not None:
> >
> > ValueError: For numerical factors, num_columns must be an int
> >
> 
> Slap the ValueError into a search engine and the first hit is 
> https://groups.google.com/forum/#!topic/pystatsmodels/KcSzNqDxv-Q
> 
> -- 
> My fellow Pythonistas, ask not what our language can do for you, ask
> what you can do for our language.
> 
> Mark Lawrence

Hi,
I don't see a solution to my problem. I find the following demo code from 

https://patsy.readthedocs.org/en/v0.1.0/API-reference.html#patsy.dmatrix

It doesn't work either on the Canopy. Does it work on your computer?
Thanks,

/////////////
demo_data("a", "x", nlevels=3)
Out[134]: 
{'a': ['a1', 'a2', 'a3', 'a1', 'a2', 'a3'],
 'x': array([ 1.76405235,  0.40015721,  0.97873798,  2.2408932 ,  1.86755799,
        -0.97727788])}

mat = dmatrix("a + x", demo_data("a", "x", nlevels=3))