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new 2690e61 Add datafusion.extract (#959)
2690e61 is described below
commit 2690e61b360a6224f1cd5b5bf29d8c082b87991d
Author: kosiew <[email protected]>
AuthorDate: Sat Nov 30 23:25:04 2024 +0800
Add datafusion.extract (#959)
* feat: add extract function as an alias for date_part
* docs: update user guide to include examples for date_part and extract
functions
* fix: update examples in user guide to use f.to_timestamp for date
extraction
---
docs/source/user-guide/common-operations/functions.rst | 9 +++++++++
python/datafusion/functions.py | 9 +++++++++
python/tests/test_functions.py | 2 ++
3 files changed, 20 insertions(+)
diff --git a/docs/source/user-guide/common-operations/functions.rst
b/docs/source/user-guide/common-operations/functions.rst
index 8d6a808..ad71c72 100644
--- a/docs/source/user-guide/common-operations/functions.rst
+++ b/docs/source/user-guide/common-operations/functions.rst
@@ -72,6 +72,15 @@ Convert to timestamps using
:py:func:`~datafusion.functions.to_timestamp`
df.select(f.to_timestamp(col('"Total"')).alias("timestamp"))
+Extracting parts of a date using :py:func:`~datafusion.functions.date_part`
(alias :py:func:`~datafusion.functions.extract`)
+
+.. ipython:: python
+
+ df.select(
+ f.date_part(literal("month"),
f.to_timestamp(col('"Total"'))).alias("month"),
+ f.extract(literal("day"), f.to_timestamp(col('"Total"'))).alias("day")
+ )
+
String
------
diff --git a/python/datafusion/functions.py b/python/datafusion/functions.py
index 6ad4c50..15ad882 100644
--- a/python/datafusion/functions.py
+++ b/python/datafusion/functions.py
@@ -128,6 +128,7 @@ __all__ = [
"empty",
"encode",
"ends_with",
+ "extract",
"exp",
"factorial",
"find_in_set",
@@ -994,6 +995,14 @@ def date_part(part: Expr, date: Expr) -> Expr:
return Expr(f.date_part(part.expr, date.expr))
+def extract(part: Expr, date: Expr) -> Expr:
+ """Extracts a subfield from the date.
+
+ This is an alias for :py:func:`date_part`.
+ """
+ return date_part(part, date)
+
+
def date_trunc(part: Expr, date: Expr) -> Expr:
"""Truncates the date to a specified level of precision."""
return Expr(f.date_trunc(part.expr, date.expr))
diff --git a/python/tests/test_functions.py b/python/tests/test_functions.py
index 0d40032..0d2fa8f 100644
--- a/python/tests/test_functions.py
+++ b/python/tests/test_functions.py
@@ -866,6 +866,7 @@ def test_temporal_functions(df):
f.to_timestamp_seconds(literal("2023-09-07 05:06:14.523952")),
f.to_timestamp_millis(literal("2023-09-07 05:06:14.523952")),
f.to_timestamp_micros(literal("2023-09-07 05:06:14.523952")),
+ f.extract(literal("day"), column("d")),
)
result = df.collect()
assert len(result) == 1
@@ -903,6 +904,7 @@ def test_temporal_functions(df):
assert result.column(9) == pa.array(
[datetime(2023, 9, 7, 5, 6, 14, 523952)] * 3, type=pa.timestamp("us")
)
+ assert result.column(10) == pa.array([31, 26, 2], type=pa.float64())
def test_case(df):
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