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DOC: Document datetime and timedelta to python's object type conversion #29557

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f478f98
DOC: document datetime/timedelta to PyObject conversion
devmt04 Aug 13, 2025
7acb9dc
Merge branch 'numpy:main' into docs-datetime-pyobject-conversion
devmt04 Aug 13, 2025
78e201c
DOC: document datetime/timedelta to PyObject conversion
devmt04 Aug 13, 2025
21e460e
DOC: document datetime/timedelta to PyObject conversion
devmt04 Aug 13, 2025
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20 changes: 20 additions & 0 deletions doc/source/reference/arrays.datetime.rst
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Expand Up @@ -309,6 +309,26 @@ us / μs microsecond +/- 2.9e5 years [290301 BC, 294241 AD]
as attosecond +/- 9.2 seconds [ 1969 AD, 1970 AD]
======== ================ ======================= ==========================


Converting datetime and timedelta to Python Object
==================================================

NumPy follows a strict protocol when converting datetime and timedelta to Python Objects (e.g., tuple, list, datetime.datetime).

For conversion of datetime to a Python Object:

- Not-a-time is returned as None.
- For days or coarser, returns a datetime.date.
- For microseconds or coarser, returns a datetime.datetime.
- For units finer than microseconds, returns an integer.

For conversion of timedelta to Python Object

- Not-a-time is returned as None.
- For microseconds or coarser, returns a datetime.timedelta.
- For Y/M/B (nonlinear units), generic units and units finer than microseconds, returns an integer.


Business day functionality
==========================

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5 changes: 3 additions & 2 deletions numpy/_core/src/multiarray/_datetime.h
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Expand Up @@ -242,6 +242,7 @@ convert_pyobject_to_timedelta(PyArray_DatetimeMetaData *meta, PyObject *obj,
/*
* Converts a datetime into a PyObject *.
*
* Not-a-time is returned as None.
* For days or coarser, returns a datetime.date.
* For microseconds or coarser, returns a datetime.datetime.
* For units finer than microseconds, returns an integer.
Expand All @@ -252,9 +253,9 @@ convert_datetime_to_pyobject(npy_datetime dt, PyArray_DatetimeMetaData *meta);
/*
* Converts a timedelta into a PyObject *.
*
* Not-a-time is returned as the string "NaT".
* Not-a-time is returned as None.
* For microseconds or coarser, returns a datetime.timedelta.
* For units finer than microseconds, returns an integer.
* For Y/M/B (nonlinear units), generic units and units finer than microseconds, returns an integer.
*/
NPY_NO_EXPORT PyObject *
convert_timedelta_to_pyobject(npy_timedelta td, PyArray_DatetimeMetaData *meta);
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6 changes: 3 additions & 3 deletions numpy/_core/src/multiarray/datetime.c
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Expand Up @@ -2761,7 +2761,7 @@ convert_pyobject_to_timedelta(PyArray_DatetimeMetaData *meta, PyObject *obj,
/*
* Converts a datetime into a PyObject *.
*
* Not-a-time is returned as the string "NaT".
* Not-a-time is returned as None.
* For days or coarser, returns a datetime.date.
* For microseconds or coarser, returns a datetime.datetime.
* For units finer than microseconds, returns an integer.
Expand Down Expand Up @@ -2945,9 +2945,9 @@ convert_timedelta_to_timedeltastruct(PyArray_DatetimeMetaData *meta,
/*
* Converts a timedelta into a PyObject *.
*
* Not-a-time is returned as the string "NaT".
* Not-a-time is returned as None.
* For microseconds or coarser, returns a datetime.timedelta.
* For units finer than microseconds, returns an integer.
* For Y/M/B (nonlinear units), generic units and units finer than microseconds, returns an integer.
*/
NPY_NO_EXPORT PyObject *
convert_timedelta_to_pyobject(npy_timedelta td, PyArray_DatetimeMetaData *meta)
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