diff options
author | Cheng Lian <lian@databricks.com> | 2016-07-23 11:41:24 -0700 |
---|---|---|
committer | Reynold Xin <rxin@databricks.com> | 2016-07-23 11:41:24 -0700 |
commit | 53b2456d1de38b9d4f18509e7b36eb3fbe09e050 (patch) | |
tree | 7a783f09648b4c86ec04b9fd26e9ef6871f2d352 /examples/src/main/python | |
parent | 86c275206605c44e1ebca2f166d62868e44bf029 (diff) | |
download | spark-53b2456d1de38b9d4f18509e7b36eb3fbe09e050.tar.gz spark-53b2456d1de38b9d4f18509e7b36eb3fbe09e050.tar.bz2 spark-53b2456d1de38b9d4f18509e7b36eb3fbe09e050.zip |
[SPARK-16380][EXAMPLES] Update SQL examples and programming guide for Python language binding
This PR is based on PR #14098 authored by wangmiao1981.
## What changes were proposed in this pull request?
This PR replaces the original Python Spark SQL example file with the following three files:
- `sql/basic.py`
Demonstrates basic Spark SQL features.
- `sql/datasource.py`
Demonstrates various Spark SQL data sources.
- `sql/hive.py`
Demonstrates Spark SQL Hive interaction.
This PR also removes hard-coded Python example snippets in the SQL programming guide by extracting snippets from the above files using the `include_example` Liquid template tag.
## How was this patch tested?
Manually tested.
Author: wm624@hotmail.com <wm624@hotmail.com>
Author: Cheng Lian <lian@databricks.com>
Closes #14317 from liancheng/py-examples-update.
Diffstat (limited to 'examples/src/main/python')
-rw-r--r-- | examples/src/main/python/sql.py | 83 | ||||
-rw-r--r-- | examples/src/main/python/sql/basic.py | 194 | ||||
-rw-r--r-- | examples/src/main/python/sql/datasource.py | 154 | ||||
-rw-r--r-- | examples/src/main/python/sql/hive.py | 96 |
4 files changed, 444 insertions, 83 deletions
diff --git a/examples/src/main/python/sql.py b/examples/src/main/python/sql.py deleted file mode 100644 index ea11d2c4c7..0000000000 --- a/examples/src/main/python/sql.py +++ /dev/null @@ -1,83 +0,0 @@ -# -# Licensed to the Apache Software Foundation (ASF) under one or more -# contributor license agreements. See the NOTICE file distributed with -# this work for additional information regarding copyright ownership. -# The ASF licenses this file to You under the Apache License, Version 2.0 -# (the "License"); you may not use this file except in compliance with -# the License. You may obtain a copy of the License at -# -# http://www.apache.org/licenses/LICENSE-2.0 -# -# Unless required by applicable law or agreed to in writing, software -# distributed under the License is distributed on an "AS IS" BASIS, -# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -# See the License for the specific language governing permissions and -# limitations under the License. -# - -from __future__ import print_function - -import os -import sys - -# $example on:init_session$ -from pyspark.sql import SparkSession -# $example off:init_session$ -from pyspark.sql.types import Row, StructField, StructType, StringType, IntegerType - - -if __name__ == "__main__": - # $example on:init_session$ - spark = SparkSession\ - .builder\ - .appName("PythonSQL")\ - .config("spark.some.config.option", "some-value")\ - .getOrCreate() - # $example off:init_session$ - - # A list of Rows. Infer schema from the first row, create a DataFrame and print the schema - rows = [Row(name="John", age=19), Row(name="Smith", age=23), Row(name="Sarah", age=18)] - some_df = spark.createDataFrame(rows) - some_df.printSchema() - - # A list of tuples - tuples = [("John", 19), ("Smith", 23), ("Sarah", 18)] - # Schema with two fields - person_name and person_age - schema = StructType([StructField("person_name", StringType(), False), - StructField("person_age", IntegerType(), False)]) - # Create a DataFrame by applying the schema to the RDD and print the schema - another_df = spark.createDataFrame(tuples, schema) - another_df.printSchema() - # root - # |-- age: long (nullable = true) - # |-- name: string (nullable = true) - - # A JSON dataset is pointed to by path. - # The path can be either a single text file or a directory storing text files. - if len(sys.argv) < 2: - path = "file://" + \ - os.path.join(os.environ['SPARK_HOME'], "examples/src/main/resources/people.json") - else: - path = sys.argv[1] - # Create a DataFrame from the file(s) pointed to by path - people = spark.read.json(path) - # root - # |-- person_name: string (nullable = false) - # |-- person_age: integer (nullable = false) - - # The inferred schema can be visualized using the printSchema() method. - people.printSchema() - # root - # |-- age: long (nullable = true) - # |-- name: string (nullable = true) - - # Creates a temporary view using the DataFrame. - people.createOrReplaceTempView("people") - - # SQL statements can be run by using the sql methods provided by `spark` - teenagers = spark.sql("SELECT name FROM people WHERE age >= 13 AND age <= 19") - - for each in teenagers.collect(): - print(each[0]) - - spark.stop() diff --git a/examples/src/main/python/sql/basic.py b/examples/src/main/python/sql/basic.py new file mode 100644 index 0000000000..74f5009581 --- /dev/null +++ b/examples/src/main/python/sql/basic.py @@ -0,0 +1,194 @@ +# +# Licensed to the Apache Software Foundation (ASF) under one or more +# contributor license agreements. See the NOTICE file distributed with +# this work for additional information regarding copyright ownership. +# The ASF licenses this file to You under the Apache License, Version 2.0 +# (the "License"); you may not use this file except in compliance with +# the License. You may obtain a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +# See the License for the specific language governing permissions and +# limitations under the License. +# + +from __future__ import print_function + +# $example on:init_session$ +from pyspark.sql import SparkSession +# $example off:init_session$ + +# $example on:schema_inferring$ +from pyspark.sql import Row +# $example off:schema_inferring$ + +# $example on:programmatic_schema$ +# Import data types +from pyspark.sql.types import * +# $example off:programmatic_schema$ + +""" +A simple example demonstrating basic Spark SQL features. +Run with: + ./bin/spark-submit examples/src/main/python/sql/basic.py +""" + + +def basic_df_example(spark): + # $example on:create_df$ + # spark is an existing SparkSession + df = spark.read.json("examples/src/main/resources/people.json") + # Displays the content of the DataFrame to stdout + df.show() + # +----+-------+ + # | age| name| + # +----+-------+ + # |null|Michael| + # | 30| Andy| + # | 19| Justin| + # +----+-------+ + # $example off:create_df$ + + # $example on:untyped_ops$ + # spark, df are from the previous example + # Print the schema in a tree format + df.printSchema() + # root + # |-- age: long (nullable = true) + # |-- name: string (nullable = true) + + # Select only the "name" column + df.select("name").show() + # +-------+ + # | name| + # +-------+ + # |Michael| + # | Andy| + # | Justin| + # +-------+ + + # Select everybody, but increment the age by 1 + df.select(df['name'], df['age'] + 1).show() + # +-------+---------+ + # | name|(age + 1)| + # +-------+---------+ + # |Michael| null| + # | Andy| 31| + # | Justin| 20| + # +-------+---------+ + + # Select people older than 21 + df.filter(df['age'] > 21).show() + # +---+----+ + # |age|name| + # +---+----+ + # | 30|Andy| + # +---+----+ + + # Count people by age + df.groupBy("age").count().show() + # +----+-----+ + # | age|count| + # +----+-----+ + # | 19| 1| + # |null| 1| + # | 30| 1| + # +----+-----+ + # $example off:untyped_ops$ + + # $example on:run_sql$ + # Register the DataFrame as a SQL temporary view + df.createOrReplaceTempView("people") + + sqlDF = spark.sql("SELECT * FROM people") + sqlDF.show() + # +----+-------+ + # | age| name| + # +----+-------+ + # |null|Michael| + # | 30| Andy| + # | 19| Justin| + # +----+-------+ + # $example off:run_sql$ + + +def schema_inference_example(spark): + # $example on:schema_inferring$ + sc = spark.sparkContext + + # Load a text file and convert each line to a Row. + lines = sc.textFile("examples/src/main/resources/people.txt") + parts = lines.map(lambda l: l.split(",")) + people = parts.map(lambda p: Row(name=p[0], age=int(p[1]))) + + # Infer the schema, and register the DataFrame as a table. + schemaPeople = spark.createDataFrame(people) + schemaPeople.createOrReplaceTempView("people") + + # SQL can be run over DataFrames that have been registered as a table. + teenagers = spark.sql("SELECT name FROM people WHERE age >= 13 AND age <= 19") + + # The results of SQL queries are Dataframe objects. + # rdd returns the content as an :class:`pyspark.RDD` of :class:`Row`. + teenNames = teenagers.rdd.map(lambda p: "Name: " + p.name).collect() + for name in teenNames: + print(name) + # Name: Justin + # $example off:schema_inferring$ + + +def programmatic_schema_example(spark): + # $example on:programmatic_schema$ + sc = spark.sparkContext + + # Load a text file and convert each line to a Row. + lines = sc.textFile("examples/src/main/resources/people.txt") + parts = lines.map(lambda l: l.split(",")) + # Each line is converted to a tuple. + people = parts.map(lambda p: (p[0], p[1].strip())) + + # The schema is encoded in a string. + schemaString = "name age" + + fields = [StructField(field_name, StringType(), True) for field_name in schemaString.split()] + schema = StructType(fields) + + # Apply the schema to the RDD. + schemaPeople = spark.createDataFrame(people, schema) + + # Creates a temporary view using the DataFrame + schemaPeople.createOrReplaceTempView("people") + + # Creates a temporary view using the DataFrame + schemaPeople.createOrReplaceTempView("people") + + # SQL can be run over DataFrames that have been registered as a table. + results = spark.sql("SELECT name FROM people") + + results.show() + # +-------+ + # | name| + # +-------+ + # |Michael| + # | Andy| + # | Justin| + # +-------+ + # $example off:programmatic_schema$ + +if __name__ == "__main__": + # $example on:init_session$ + spark = SparkSession \ + .builder \ + .appName("PythonSQL") \ + .config("spark.some.config.option", "some-value") \ + .getOrCreate() + # $example off:init_session$ + + basic_df_example(spark) + schema_inference_example(spark) + programmatic_schema_example(spark) + + spark.stop() diff --git a/examples/src/main/python/sql/datasource.py b/examples/src/main/python/sql/datasource.py new file mode 100644 index 0000000000..0bdc3d66ff --- /dev/null +++ b/examples/src/main/python/sql/datasource.py @@ -0,0 +1,154 @@ +# +# Licensed to the Apache Software Foundation (ASF) under one or more +# contributor license agreements. See the NOTICE file distributed with +# this work for additional information regarding copyright ownership. +# The ASF licenses this file to You under the Apache License, Version 2.0 +# (the "License"); you may not use this file except in compliance with +# the License. You may obtain a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +# See the License for the specific language governing permissions and +# limitations under the License. +# + +from __future__ import print_function + +from pyspark.sql import SparkSession +# $example on:schema_merging$ +from pyspark.sql import Row +# $example off:schema_merging$ + +""" +A simple example demonstrating Spark SQL data sources. +Run with: + ./bin/spark-submit examples/src/main/python/sql/datasource.py +""" + + +def basic_datasource_example(spark): + # $example on:generic_load_save_functions$ + df = spark.read.load("examples/src/main/resources/users.parquet") + df.select("name", "favorite_color").write.save("namesAndFavColors.parquet") + # $example off:generic_load_save_functions$ + + # $example on:manual_load_options$ + df = spark.read.load("examples/src/main/resources/people.json", format="json") + df.select("name", "age").write.save("namesAndAges.parquet", format="parquet") + # $example off:manual_load_options$ + + # $example on:direct_sql$ + df = spark.sql("SELECT * FROM parquet.`examples/src/main/resources/users.parquet`") + # $example off:direct_sql$ + + +def parquet_example(spark): + # $example on:basic_parquet_example$ + peopleDF = spark.read.json("examples/src/main/resources/people.json") + + # DataFrames can be saved as Parquet files, maintaining the schema information. + peopleDF.write.parquet("people.parquet") + + # Read in the Parquet file created above. + # Parquet files are self-describing so the schema is preserved. + # The result of loading a parquet file is also a DataFrame. + parquetFile = spark.read.parquet("people.parquet") + + # Parquet files can also be used to create a temporary view and then used in SQL statements. + parquetFile.createOrReplaceTempView("parquetFile") + teenagers = spark.sql("SELECT name FROM parquetFile WHERE age >= 13 AND age <= 19") + teenagers.show() + # +------+ + # | name| + # +------+ + # |Justin| + # +------+ + # $example off:basic_parquet_example$ + + +def parquet_schema_merging_example(spark): + # $example on:schema_merging$ + # spark is from the previous example. + # Create a simple DataFrame, stored into a partition directory + sc = spark.sparkContext + + squaresDF = spark.createDataFrame(sc.parallelize(range(1, 6)) + .map(lambda i: Row(single=i, double=i ** 2))) + squaresDF.write.parquet("data/test_table/key=1") + + # Create another DataFrame in a new partition directory, + # adding a new column and dropping an existing column + cubesDF = spark.createDataFrame(sc.parallelize(range(6, 11)) + .map(lambda i: Row(single=i, triple=i ** 3))) + cubesDF.write.parquet("data/test_table/key=2") + + # Read the partitioned table + mergedDF = spark.read.option("mergeSchema", "true").parquet("data/test_table") + mergedDF.printSchema() + + # The final schema consists of all 3 columns in the Parquet files together + # with the partitioning column appeared in the partition directory paths. + # root + # |-- double: long (nullable = true) + # |-- single: long (nullable = true) + # |-- triple: long (nullable = true) + # |-- key: integer (nullable = true) + # $example off:schema_merging$ + + +def json_dataset_examplg(spark): + # $example on:json_dataset$ + # spark is from the previous example. + sc = spark.sparkContext + + # A JSON dataset is pointed to by path. + # The path can be either a single text file or a directory storing text files + path = "examples/src/main/resources/people.json" + peopleDF = spark.read.json(path) + + # The inferred schema can be visualized using the printSchema() method + peopleDF.printSchema() + # root + # |-- age: long (nullable = true) + # |-- name: string (nullable = true) + + # Creates a temporary view using the DataFrame + peopleDF.createOrReplaceTempView("people") + + # SQL statements can be run by using the sql methods provided by spark + teenagerNamesDF = spark.sql("SELECT name FROM people WHERE age BETWEEN 13 AND 19") + teenagerNamesDF.show() + # +------+ + # | name| + # +------+ + # |Justin| + # +------+ + + # Alternatively, a DataFrame can be created for a JSON dataset represented by + # an RDD[String] storing one JSON object per string + jsonStrings = ['{"name":"Yin","address":{"city":"Columbus","state":"Ohio"}}'] + otherPeopleRDD = sc.parallelize(jsonStrings) + otherPeople = spark.read.json(otherPeopleRDD) + otherPeople.show() + # +---------------+----+ + # | address|name| + # +---------------+----+ + # |[Columbus,Ohio]| Yin| + # +---------------+----+ + # $example off:json_dataset$ + +if __name__ == "__main__": + spark = SparkSession \ + .builder \ + .appName("PythonSQL") \ + .getOrCreate() + + basic_datasource_example(spark) + parquet_example(spark) + parquet_schema_merging_example(spark) + json_dataset_examplg(spark) + + spark.stop() diff --git a/examples/src/main/python/sql/hive.py b/examples/src/main/python/sql/hive.py new file mode 100644 index 0000000000..d9ce5cef1f --- /dev/null +++ b/examples/src/main/python/sql/hive.py @@ -0,0 +1,96 @@ +# +# Licensed to the Apache Software Foundation (ASF) under one or more +# contributor license agreements. See the NOTICE file distributed with +# this work for additional information regarding copyright ownership. +# The ASF licenses this file to You under the Apache License, Version 2.0 +# (the "License"); you may not use this file except in compliance with +# the License. You may obtain a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +# See the License for the specific language governing permissions and +# limitations under the License. +# + +from __future__ import print_function + +# $example on:spark_hive$ +from os.path import expanduser, join + +from pyspark.sql import SparkSession +from pyspark.sql import Row +# $example off:spark_hive$ + +""" +A simple example demonstrating Spark SQL Hive integration. +Run with: + ./bin/spark-submit examples/src/main/python/sql/hive.py +""" + + +if __name__ == "__main__": + # $example on:spark_hive$ + # warehouse_location points to the default location for managed databases and tables + warehouse_location = 'file:${system:user.dir}/spark-warehouse' + + spark = SparkSession \ + .builder \ + .appName("PythonSQL") \ + .config("spark.sql.warehouse.dir", warehouse_location) \ + .enableHiveSupport() \ + .getOrCreate() + + # spark is an existing SparkSession + spark.sql("CREATE TABLE IF NOT EXISTS src (key INT, value STRING)") + spark.sql("LOAD DATA LOCAL INPATH 'examples/src/main/resources/kv1.txt' INTO TABLE src") + + # Queries are expressed in HiveQL + spark.sql("SELECT * FROM src").show() + # +---+-------+ + # |key| value| + # +---+-------+ + # |238|val_238| + # | 86| val_86| + # |311|val_311| + # ... + + # Aggregation queries are also supported. + spark.sql("SELECT COUNT(*) FROM src").show() + # +--------+ + # |count(1)| + # +--------+ + # | 500 | + # +--------+ + + # The results of SQL queries are themselves DataFrames and support all normal functions. + sqlDF = spark.sql("SELECT key, value FROM src WHERE key < 10 ORDER BY key") + + # The items in DaraFrames are of type Row, which allows you to access each column by ordinal. + stringsDS = sqlDF.rdd.map(lambda row: "Key: %d, Value: %s" % (row.key, row.value)) + for record in stringsDS.collect(): + print(record) + # Key: 0, Value: val_0 + # Key: 0, Value: val_0 + # Key: 0, Value: val_0 + # ... + + # You can also use DataFrames to create temporary views within a SparkSession. + Record = Row("key", "value") + recordsDF = spark.createDataFrame(map(lambda i: Record(i, "val_" + str(i)), range(1, 101))) + recordsDF.createOrReplaceTempView("records") + + # Queries can then join DataFrame data with data stored in Hive. + spark.sql("SELECT * FROM records r JOIN src s ON r.key = s.key").show() + # +---+------+---+------+ + # |key| value|key| value| + # +---+------+---+------+ + # | 2| val_2| 2| val_2| + # | 4| val_4| 4| val_4| + # | 5| val_5| 5| val_5| + # ... + # $example off:spark_hive$ + + spark.stop() |