zhengruifeng commented on code in PR #44794:
URL: https://github.com/apache/spark/pull/44794#discussion_r1458467248
##########
python/pyspark/sql/functions/builtin.py:
##########
@@ -1488,31 +1533,75 @@ def acos(col: "ColumnOrName") -> Column:
Parameters
----------
col : :class:`~pyspark.sql.Column` or str
- target column to compute on.
+ The target column or expression to compute the inverse cosine on.
Returns
-------
:class:`~pyspark.sql.Column`
- inverse cosine of `col`, as if computed by `java.lang.Math.acos()`
+ A new column object representing the inverse cosine of the input.
Examples
--------
- >>> df = spark.range(1, 3)
- >>> df.select(acos(df.id)).show()
- +--------+
- |ACOS(id)|
- +--------+
- | 0.0|
- | NaN|
- +--------+
+ Example 1: Compute the inverse cosine of a column of numbers
+
+ >>> from pyspark.sql import functions as sf
+ >>> df = spark.createDataFrame([(1, 0.5), (2, -0.5), (3, 1.0)], ["id",
"value"])
+ >>> df.select(sf.acos(df.value)).show()
+ +------------------+
+ | ACOS(value)|
+ +------------------+
+ |1.0471975511965979|
Review Comment:
for trigonometric functions' example, what about making them use or return
some special values? e.g.
```
In [26]: df = spark.createDataFrame([(-1.0, 0.5), (-0.5, -0.5), (0.0, 1.0),
(0.5, 0.0), (1.0, 1.0)], ["v1", "v2"])
In [27]: df.select("v1", sf.acos("v1"), sf.degrees(sf.acos("v1"))).show()
+----+------------------+------------------+
| v1| ACOS(v1)| DEGREES(ACOS(v1))|
+----+------------------+------------------+
|-1.0| 3.141592653589...| 180.0|
|-0.5|2.0943951023931...|120.00000000000...|
| 0.0|1.5707963267948...| 90.0|
| 0.5|1.0471975511965...| 60.00000000000...|
| 1.0| 0.0| 0.0|
+----+------------------+------------------+
```
and we'd better use `...` at the last of numbers, since the computation
result may vary slightly on different envs.
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