TypeError when using ShiftedPearsonCorrelation with a constant time series

[ckae95]

Description

Error is thrown when using ShiftedPearsonCorrelation and a time series (i.e. a column in the data frame) is constant.

Steps/Code to Reproduce

This is the example as shown in the documentation with an additional column 'E' which is constant.

from giottotime.causality_tests.shifted_pearson_correlation import ShiftedPearsonCorrelation
import pandas.util.testing as testing
import numpy as np
data = testing.makeTimeDataFrame(freq="s")
data['E'] = np.ones(len(data))
spc = ShiftedPearsonCorrelation(target_col="A")
spc.fit(data)
spc.best_shifts_

spc.transform(data)

Expected Results

No error is thrown.

Actual Results

---

TypeError Traceback (most recent call last)
in
8 spc.best_shifts_
9
---> 10 spc.transform(data)

~/anaconda3/envs/time/lib/python3.7/site-packages/giottotime/causality_tests/shifted_pearson_correlation.py in transform(self, data)
119 for col in data_t:
120 if col != self.target_col:
--> 121 data_t[col] = data_t[col].shift(self.best_shifts_[col][self.target_col])
122
123 if self.dropna:

~/anaconda3/envs/time/lib/python3.7/site-packages/pandas/core/series.py in shift(self, periods, freq, axis, fill_value)
4371 def shift(self, periods=1, freq=None, axis=0, fill_value=None):
4372 return super().shift(
-> 4373 periods=periods, freq=freq, axis=axis, fill_value=fill_value
4374 )
4375

~/anaconda3/envs/time/lib/python3.7/site-packages/pandas/core/generic.py in shift(self, periods, freq, axis, fill_value)
9397 if freq is None:
9398 new_data = self._data.shift(
-> 9399 periods=periods, axis=block_axis, fill_value=fill_value
9400 )
9401 else:

~/anaconda3/envs/time/lib/python3.7/site-packages/pandas/core/internals/managers.py in shift(self, **kwargs)
570
571 def shift(self, **kwargs):
--> 572 return self.apply("shift", **kwargs)
573
574 def fillna(self, **kwargs):

~/anaconda3/envs/time/lib/python3.7/site-packages/pandas/core/internals/managers.py in apply(self, f, axes, filter, do_integrity_check, consolidate, **kwargs)
436 kwargs[k] = obj.reindex(b_items, axis=axis, copy=align_copy)
437
--> 438 applied = getattr(b, f)(**kwargs)
439 result_blocks = _extend_blocks(applied, result_blocks)
440

~/anaconda3/envs/time/lib/python3.7/site-packages/pandas/core/internals/blocks.py in shift(self, periods, axis, fill_value)
1351 else:
1352 axis_indexer[axis] = slice(periods, None)
-> 1353 new_values[tuple(axis_indexer)] = fill_value
1354
1355 # restore original order

TypeError: slice indices must be integers or None or have an index method

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