python - 如何从时间戳中减去充满日期的 pandas.core.series.Series ，以找到每行日期与该时间戳日期的差异？

Question

我想从时间戳中减去日期。settings.dataset_end_date 是一个 pandas._libs.tslibs.timestamps.Timestamp引用['date_of_patent']是一个pandas.core.series.Seriespatent['date'] 是一个 pandas.core.series.Series

我创建了一个示例代码，其中我已经执行了似乎工作正常的 dtypes 转换，但是当将其应用到我的完整数据集时，我收到了上面的错误。

```python

settings.dataset_end_date = pd.to_datetime('2019-01-01')

#Find citations and dates from 'uspatentcitation' and 'patent'
citation = citation.rename(columns={'citation_id': 'id', 'date_citation': 'date_of_patent', 'date_id': 'date_cited'})

# Find time between citation and target patent grant date
citation['delta_citation'] = (citation['date_cited'].subtract(citation['date_of_patent'])).dt.days/365

# Find the years available
citation['years_available'] = (settings.dataset_end_date - citation['date_of_patent']).dt.days/365
patent['years_available'] = (settings.dataset_end_date - patent['date']).dt.days/365
```

I expect column with differences in years

```python
____________________________________________________________________
Error_______________________________________________________________

OverflowError                             Traceback (most recent call last)
<ipython-input-70-300ff02274d2> in <module>()
      5 
      6 # Find time between citation and target patent grant date
----> 7 citation['delta_citation'] = (citation['date_cited'] - citation['date_of_patent']).dt.days/365
      8 
      9 # Find the years available (used for nulling where the dataset ends before a time could be reached)

/anaconda/envs/py35/lib/python3.5/site-packages/pandas/core/ops.py in wrapper(left, right)
   1550             # test_dt64_series_add_intlike, which the index dispatching handles
   1551             # specifically.
-> 1552             result = dispatch_to_index_op(op, left, right, pd.DatetimeIndex)
   1553             return construct_result(left, result,
   1554                                     index=left.index, name=res_name,

/anaconda/envs/py35/lib/python3.5/site-packages/pandas/core/ops.py in dispatch_to_index_op(op, left, right, index_class)
   1189         left_idx = left_idx._shallow_copy(freq=None)
   1190     try:
-> 1191         result = op(left_idx, right)
   1192     except NullFrequencyError:
   1193         # DatetimeIndex and TimedeltaIndex with freq == None raise ValueError

/anaconda/envs/py35/lib/python3.5/site-packages/pandas/core/ops.py in wrapper(left, right)
   1550             # test_dt64_series_add_intlike, which the index dispatching handles
   1551             # specifically.
-> 1552             result = dispatch_to_index_op(op, left, right, pd.DatetimeIndex)
   1553             return construct_result(left, result,
   1554                                     index=left.index, name=res_name,

/anaconda/envs/py35/lib/python3.5/site-packages/pandas/core/ops.py in dispatch_to_index_op(op, left, right, index_class)
   1189         left_idx = left_idx._shallow_copy(freq=None)
1190     try:
-> 1191         result = op(left_idx, right)
   1192     except NullFrequencyError:
   1193         # DatetimeIndex and TimedeltaIndex with freq == None raise ValueError

/anaconda/envs/py35/lib/python3.5/site-packages/pandas/core/ops.py in rsub(left, right)
    146 
    147 def rsub(left, right):
--> 148     return right - left
    149 
    150 

/anaconda/envs/py35/lib/python3.5/site-packages/pandas/core/indexes/datetimelike.py in __sub__(self, other)
    499         def __sub__(self, other):
    500             # dispatch to ExtensionArray implementation
--> 501             result = self._data.__sub__(maybe_unwrap_index(other))
    502             return wrap_arithmetic_op(self, other, result)
    503 

/anaconda/envs/py35/lib/python3.5/site-packages/pandas/core/arrays/datetimelike.py in __sub__(self, other)
   1273         elif is_datetime64_dtype(other) or is_datetime64tz_dtype(other):
   1274             # DatetimeIndex, ndarray[datetime64]
-> 1275             result = self._sub_datetime_arraylike(other)
   1276         elif is_period_dtype(other):
   1277             # PeriodIndex

/anaconda/envs/py35/lib/python3.5/site-packages/pandas/core/arrays/datetimes.py in _sub_datetime_arraylike(self, other)
    722         other_i8 = other.asi8
    723         new_values = checked_add_with_arr(self_i8, -other_i8,
--> 724                                           arr_mask=self._isnan)
    725         if self._hasnans or other._hasnans:
    726             mask = (self._isnan) | (other._isnan)

/anaconda/envs/py35/lib/python3.5/site-packages/pandas/core/algorithms.py in checked_add_with_arr(arr, b, arr_mask, b_mask)
    936 
    937     if to_raise:
--> 938         raise OverflowError("Overflow in int64 addition")
    939     return arr + b
    940 

OverflowError: Overflow in int64 addition

I have updated my Pandas and if I only run this part of the code:

    ```python
     # Find the years available
        citation['years_available'] = (settings.dataset_end_date - citation['date_of_patent']).dt.days/365
        patent['years_available'] = (settings.dataset_end_date - patent['date']).dt.days/365
    ```

I get the following error:

```python
/anaconda/envs/py35/lib/python3.5/site-packages/pandas/core/indexes/datetimelike.py in __sub__(self, other)
    499         return super()._convert_scalar_indexer(key, kind=kind)
    500 
--> 501     @classmethod
    502     def _add_datetimelike_methods(cls):
    503         """/anaconda/envs/py35/lib/python3.5/site-packages/pandas/core/arrays/datetimelike.py in __sub__(self, other)
   1253             return NotImplemented
   1254 
-> 1255         if is_timedelta64_dtype(result) and isinstance(result, np.ndarray):
   1256             from pandas.core.arrays import TimedeltaArray
   1257 

/anaconda/envs/py35/lib/python3.5/site-packages/pandas/core/arrays/datetimes.py in _sub_datetimelike_scalar(self, other)
    761 
    762     # -----------------------------------------------------------------
--> 763     # Comparison Methods
    764 
    765     _create_comparison_method = classmethod(_dt_array_cmp)

/anaconda/envs/py35/lib/python3.5/site-packages/pandas/core/algorithms.py in checked_add_with_arr(arr, b, arr_mask, b_mask)
    936 def checked_add_with_arr(arr, b, arr_mask=None, b_mask=None):
    937     """
--> 938     Perform array addition that checks for underflow and overflow.
    939 
    940     Performs the addition of an int64 array and an int64 integer (or array)

OverflowError: Overflow in int64 addition

Answer 1

检查您的日期时间列是否实际上是日期时间类型，否则在减去时间戳之前将其转换:

citation['date_of_patent'] = pd.to_datetime(citation['date_of_patent'])
citation['date_cited'] = pd.to_datetime(citation['date_cited'])