Enabling for Conversion to/from Pandas in Python
Arrow is available as an optimization when converting a Spark DataFrame to a Pandas DataFrame using the call toPandas() and when creating a Spark DataFrame from a Pandas DataFrame with createDataFrame(pandas_df). To use Arrow when executing these calls, users need to first set the Spark configuration spark.sql.execution.arrow.enabled to true. This is disabled by default.
In addition, optimizations enabled by
spark.sql.execution.arrow.enabled
could fallback automatically to non-Arrow optimization implementation if an error occurs before the actual computation within Spark. This can be controlled by
spark.sql.execution.arrow.fallback.enabled.
Example Python code
import findspark
findspark.init()
import pandas as pd
from pyspark.sql.functions import col, pandas_udf
from pyspark.sql.types import LongType
from pyspark.sql import SparkSession
spark = SparkSession.builder.getOrCreate()
# Declare the function and create the UDF
def multiply_func(a, b):
return a * b
multiply = pandas_udf(multiply_func, returnType=LongType())
# The function for a pandas_udf should be able to execute with local Pandas data
x = pd.Series([1, 2, 3])
print(multiply_func(x, x))
# 0 1
# 1 4
# 2 9
# dtype: int64
# Create a Spark DataFrame, 'spark' is an existing SparkSession
df = spark.createDataFrame(pd.DataFrame(x, columns=["x"]))
# Execute function as a Spark vectorized UDF
df.select(col("x")*col("x")).show()
'''
0 1
1 4
2 9
dtype: int64
+-------+
|(x * x)|
+-------+
| 1|
| 4|
| 9|
+-------+
'''
Some issue:
import numpy as np
import pandas as pd
# Enable Arrow-based columnar data transfers
spark.conf.set("spark.sql.execution.arrow.enabled", "true")
# Generate a Pandas DataFrame
pdf = pd.DataFrame(np.random.rand(100, 3))
# Create a Spark DataFrame from a Pandas DataFrame using Arrow
df = spark.createDataFrame(pdf)
# Convert the Spark DataFrame back to a Pandas DataFrame using Arrow
result_pdf = df.select("*").toPandas()
here is the error when running creaeDataframe from pandas dataframe, when spark.sql.execution.arrow.enabled is true
/home/dv6/spark/spark/python/pyspark/sql/session.py:714: UserWarning: createDataFrame attempted Arrow optimization because 'spark.sql.execution.arrow.enabled' is set to true; however, failed by the reason below:
An error occurred while calling z:org.apache.spark.sql.api.python.PythonSQLUtils.readArrowStreamFromFile.
: java.lang.IllegalArgumentException
at java.nio.ByteBuffer.allocate(ByteBuffer.java:334)
at org.apache.arrow.vector.ipc.message.MessageSerializer.readMessage(MessageSerializer.java:543)
at org.apache.spark.sql.execution.arrow.ArrowConverters$$anon$3.readNextBatch(ArrowConverters.scala:243)
at org.apache.spark.sql.execution.arrow.ArrowConverters$$anon$3.<init>(ArrowConverters.scala:229)
at org.apache.spark.sql.execution.arrow.ArrowConverters$.getBatchesFromStream(ArrowConverters.scala:228)
at org.apache.spark.sql.execution.arrow.ArrowConverters$$anonfun$readArrowStreamFromFile$2.apply(ArrowConverters.scala:216)
at org.apache.spark.sql.execution.arrow.ArrowConverters$$anonfun$readArrowStreamFromFile$2.apply(ArrowConverters.scala:214)
at org.apache.spark.util.Utils$.tryWithResource(Utils.scala:2543)
at org.apache.spark.sql.execution.arrow.ArrowConverters$.readArrowStreamFromFile(ArrowConverters.scala:214)
at org.apache.spark.sql.api.python.PythonSQLUtils$.readArrowStreamFromFile(PythonSQLUtils.scala:46)
at org.apache.spark.sql.api.python.PythonSQLUtils.readArrowStreamFromFile(PythonSQLUtils.scala)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at py4j.reflection.MethodInvoker.invoke(MethodInvoker.java:244)
at py4j.reflection.ReflectionEngine.invoke(ReflectionEngine.java:357)
at py4j.Gateway.invoke(Gateway.java:282)
at py4j.commands.AbstractCommand.invokeMethod(AbstractCommand.java:132)
at py4j.commands.CallCommand.execute(CallCommand.java:79)
at py4j.GatewayConnection.run(GatewayConnection.java:238)
at java.lang.Thread.run(Thread.java:748)
Attempting non-optimization as 'spark.sql.execution.arrow.fallback.enabled' is set to true.
warnings.warn(msg)
Work around, set OS environment variable
export ARROW_PRE_0_15_IPC_FORMAT=1
Then run Python code
(spark) dv6@dv6:~$ export ARROW_PRE_0_15_IPC_FORMAT=1
(spark) dv6@dv6:~$ python
Python 3.6.10 |Anaconda, Inc.| (default, Jan 7 2020, 21:14:29)
[GCC 7.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import findspark
>>> findspark.init()
>>> import pandas as pd
>>>
>>> from pyspark.sql.functions import col, pandas_udf
>>> from pyspark.sql.types import LongType
>>> from pyspark.sql import SparkSession
>>>
>>> spark = SparkSession.builder.getOrCreate()
20/04/12 12:29:18 WARN NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
Setting default log level to "WARN".
To adjust logging level use sc.setLogLevel(newLevel). For SparkR, use setLogLevel(newLevel).
20/04/12 12:29:20 WARN Utils: Service 'SparkUI' could not bind on port 4040. Attempting port 4041.
20/04/12 12:29:20 WARN Utils: Service 'SparkUI' could not bind on port 4041. Attempting port 4042.
20/04/12 12:29:20 WARN Utils: Service 'SparkUI' could not bind on port 4042. Attempting port 4043.
20/04/12 12:29:20 WARN Utils: Service 'SparkUI' could not bind on port 4043. Attempting port 4044.
>>> import numpy as np
>>> import pandas as pd
>>>
>>> # Enable Arrow-based columnar data transfers
... spark.conf.set("spark.sql.execution.arrow.enabled", "true")
>>>
>>> # Generate a Pandas DataFrame
... pdf = pd.DataFrame(np.random.rand(100, 3))
>>> pdf
0 1 2
0 0.937892 0.387147 0.590136
1 0.007276 0.961907 0.156945
2 0.212474 0.048127 0.936995
3 0.074513 0.579899 0.803862
4 0.324786 0.352669 0.602877
.. ... ... ...
95 0.164290 0.376453 0.388663
96 0.014815 0.709746 0.615609
97 0.797867 0.563372 0.132668
98 0.755495 0.589192 0.793425
99 0.505420 0.672960 0.452064
[100 rows x 3 columns]
>>> df = spark.createDataFrame(pdf)
>>> # Convert the Spark DataFrame back to a Pandas DataFrame using Arrow
... result_pdf = df.select("*").toPandas()
>>>