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

[Robert]

On Wednesday, December 16, 2015 at 5:44:21 AM UTC-5, 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

BTW, I use Python 2.7 on Canopy. 

patsy: VERSION    0.4.0

Thanks,