HyukjinKwon commented on code in PR #43301:
URL: https://github.com/apache/spark/pull/43301#discussion_r1354119362
##########
python/pyspark/sql/readwriter.py:
##########
@@ -505,24 +506,71 @@ def parquet(self, *paths: str, **options:
"OptionalPrimitiveType") -> "DataFrame
.. # noqa
+ Returns
+ -------
+ :class:`DataFrame`
+ A DataFrame containing the data from the Parquet files.
+
Examples
--------
+ Create sample dataframes.
+
+ >>> df = spark.createDataFrame(
+ ... [(10, "Alice"), (15, "Bob"), (20, "Tom")], schema=["age",
"name"])
+ >>> df2 = spark.createDataFrame([(70, "Alice"), (80, "Bob")],
schema=["height", "name"])
+
Write a DataFrame into a Parquet file and read it back.
>>> import tempfile
>>> with tempfile.TemporaryDirectory() as d:
- ... # Write a DataFrame into a Parquet file
- ... spark.createDataFrame(
- ... [{"age": 100, "name": "Hyukjin Kwon"}]
- ... ).write.mode("overwrite").format("parquet").save(d)
+ ... # Write a DataFrame into a Parquet file.
+ ... df.write.mode("overwrite").format("parquet").save(d)
...
... # Read the Parquet file as a DataFrame.
- ... spark.read.parquet(d).show()
- +---+------------+
- |age| name|
- +---+------------+
- |100|Hyukjin Kwon|
- +---+------------+
+ ... spark.read.parquet(d).orderBy("name").show()
+ +---+-----+
+ |age| name|
+ +---+-----+
+ | 10|Alice|
+ | 15| Bob|
+ | 20| Tom|
+ +---+-----+
+
+ Read a Parquet file with a specific column.
+
+ >>> with tempfile.TemporaryDirectory as d:
+ ... df.write.mode("overwrite").format("parquet").save(d)
+ ...
+ ... # Read the Parquet file with only the 'name' column.
+ ... spark.read.schema("name
string").parquet(d).orderBy("name").show()
+ +-----+
+ | name|
+ +-----+
+ |Alice|
+ | Bob|
+ | Tom|
+ +-----+
+
+ Read multiple Parquet files and merge schema.
+
+ >>> with tempfile.TemporaryDirectory() as d1,
tempfile.TemporaryDirectory() as d2:
+ ... df.write.mode("overwrite").format("parquet").save(d1)
+ ... df2.write.mode("overwrite").format("parquet").save(d2)
+ ...
+ ... spark.read.option(
+ ... "mergeSchema", "true"
+ ... ).parquet(d1, d2).select(
+ ... "name", "age", "height"
+ ... ).orderBy("name", "age").show()
+ +-----+----+------+
+ | name| age|height|
+ +-----+----+------+
+ |Alice|null| 70|
+ |Alice| 10| null|
+ | Bob|null| 80|
+ | Bob| 15| null|
+ | Tom| 20| null|
+ +-----+----+------+
Review Comment:
```suggestion
+-----+----+------+
| name| age|height|
+-----+----+------+
|Alice|NULL| 70|
|Alice| 10| NULL|
| Bob|NULL| 80|
| Bob| 15| NULL|
| Tom| 20| NULL|
+-----+----+------+
```
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