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

[Robert]

On Wednesday, December 16, 2015 at 5:57:04 AM UTC-5, Robert wrote:
> 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,

When I use this code snippet, copied from the wb, it is also wrong:

import numpy as np
import pandas as pd
import patsy

time = np.tile([1, 2, 3, 4], 3)
country = np.repeat(['a', 'b', 'c'], 4)
event_int = np.random.randint(0, 2, size=len(time))

df = pd.DataFrame({'event_int':event_int, 'time_day':time, 'country':country})

f0 = 'event_int ~ C(time_day):C(country) - 1'
y,X0 = patsy.dmatrices(f0, df, return_type='dataframe')
print len(X0.columns)

I am new to these packages. I don't know why it is correct for other users.
Thanks,