'UFuncTypeError' thrown in the DetrendedFeature function when changing the frequency to months or weeks

[ckae95]

Description

'UFuncTypeError' thrown in the DetrendedFeature function when changing the frequency to months or weeks

Steps/Code to Reproduce

import pandas as pd
from giottotime.feature_creation import DetrendedFeature
from giottotime.models import PolynomialTrend
model = PolynomialTrend(order=2)
detrend_feature = DetrendedFeature(trend_model=model)
time_index = pd.date_range("2011-01-01", "2011-11-01", freq='M')
X = pd.DataFrame(range(0, len(time_index)), index=time_index)
detrend_feature.transform(X)

Comment

It works e.g. if I set the frequency to days or hours but not for weeks or months.

Error message

UFuncTypeError Traceback (most recent call last)
in
4 detrend_feature = DetrendedFeature(trend_model=model)
5
----> 6 detrend_feature.transform(pd.DataFrame(test_all, index=time_index))

~/anaconda3/envs/time/lib/python3.7/site-packages/giottotime/feature_creation/index_dependent_features/trend_features.py in transform(self, time_series)
73 """
74 self.trend_model.fit(time_series)
---> 75 time_series_t = self.trend_model.transform(time_series)
76 time_series_t = self._rename_columns(time_series_t)
77 return time_series_t

~/anaconda3/envs/time/lib/python3.7/site-packages/giottotime/models/trend_models/polynomial_trend.py in transform(self, ts)
118
119 p = np.poly1d(self.model_weights_)
--> 120 time_steps = (ts.index - self.t0_) / self.period_
121
122 predictions = pd.Series(index=ts.index, data=[p(t) for t in time_steps])

~/anaconda3/envs/time/lib/python3.7/site-packages/pandas/core/indexes/timedeltas.py in method(self, other)
45
46 def method(self, other):
---> 47 result = meth(self._data, maybe_unwrap_index(other))
48 return wrap_arithmetic_op(self, other, result)
49

~/anaconda3/envs/time/lib/python3.7/site-packages/pandas/core/arrays/timedeltas.py in truediv(self, other)
531 elif lib.is_scalar(other):
532 # assume it is numeric
--> 533 result = self._data / other
534 freq = None
535 if self.freq is not None:

UFuncTypeError: ufunc 'true_divide' cannot use operands with types dtype('<m8[ns]') and dtype('O')

Versions

Darwin-18.7.0-x86_64-i386-64bit
Python 3.7.5 (default, Oct 25 2019, 10:52:18)
[Clang 4.0.1 (tags/RELEASE_401/final)]
NumPy 1.18.0
SciPy 1.4.1
joblib 0.14.1
Scikit-Learn 0.22
giotto-Learn 0.1.3
giotto-time 0.1.0