py4j

Using py4j to send matrices to from Python to Java as int[][] arrays

由 风流意气都作罢 提交于 2019-12-21 21:06:26
问题 I've been using py4j to build a user-friendly Python library around a less user-friendly Java library. For the most part, this has been a breeze, and py4j has been a great tool. However, I've come across a snag when sending matrices between Python and Java. Specifically, I have a static function in java that accepts, as its arguments, an integer matrix: public class MyClass { // ... public static MyObject create(int[][] matrix) { // ... } } I'd like to be able to call this from Py4j like so:

Why can't PySpark find py4j.java_gateway?

由 梦想与她 提交于 2019-12-17 10:23:21
问题 I installed Spark, ran the sbt assembly, and can open bin/pyspark with no problem. However, I am running into problems loading the pyspark module into ipython. I'm getting the following error: In [1]: import pyspark --------------------------------------------------------------------------- ImportError Traceback (most recent call last) <ipython-input-1-c15ae3402d12> in <module>() ----> 1 import pyspark /usr/local/spark/python/pyspark/__init__.py in <module>() 61 62 from pyspark.conf import

JavaPackage object is not callable error: Pyspark

由 ≯℡__Kan透↙ 提交于 2019-12-14 03:55:48
问题 Operations like dataframe.show() , sQLContext.read.json works fine , but most functions gives "JavaPackage object is not callable error" . eg : when i do dataFrame.withColumn(field_name, monotonically_increasing_id()) I get an error File "/tmp/spark-cd423f35-9572-45ee-b159-1b2732afa2a6/userFiles-3a6e1729-95f4-468b-914c-c706369bf2a6/Transformations.py", line 64, in add_id_column self.dataFrame = self.dataFrame.withColumn(field_name, monotonically_increasing_id()) File "/home/himaprasoon/apps

Py4j Cannot connect to Java Server

由 爷，独闯天下 提交于 2019-12-13 03:42:34
问题 I was trying to write a simple program to setup a connection between python and java using py4j. I wrote the following two lines hoping that everything would run since I'm not making any changes from py4j.java_gateway import JavaGateway, GatewayParameters gateway = JavaGateway(gateway_parameters=GatewayParameters(port=25335)) random = gateway.jvm.java.util.Random() which resulted in the following error py4j.protocol.Py4JNetworkError: An error occurred while trying to connect to the Java

py4j.protocol.Py4JNetworkError : An error occurred while trying to connect to the Java server

由 好久不见. 提交于 2019-12-12 11:11:52
问题 I have the following simple example from the py4j document: from py4j.java_gateway import JavaGateway def main(): print("Hello") gateway = JavaGateway() # connect to the JVM random = gateway.jvm.java.util.Random() # create a java.util.Random instance number1 = random.nextInt(10) # call the Random.nextInt method number2 = random.nextInt(10) print(number1,number2) if __name__ == '__main__': main() I tried to run it, but get the following error: Traceback (most recent call last): File "/Users

Send a Python object to Java using Py4j

由 ぐ巨炮叔叔 提交于 2019-12-09 18:16:28
问题 I'm trying to extend the example from this tutorial by sending Python objects to Java. While the example code which exchanges String objects between Python and Java works fine, when I try to replace it with my own Python object (Event), an error regarding object_id is displayed. Python Code: class Event(object): #some content here stack = gateway.entry_point.getStack() event = Event() stack.push(event) Error: Traceback (most recent call last): File "/home/******/src/py4jSample.py", line 19,

Implement a java UDF and call it from pyspark

由 ↘锁芯ラ 提交于 2019-12-09 09:46:54
问题 I need to create a UDF to be used in pyspark python which uses a java object for its internal calculations. If it were a simple python I would do something like: def f(x): return 7 fudf = pyspark.sql.functions.udf(f,pyspark.sql.types.IntegerType()) and call it using: df = sqlContext.range(0,5) df2 = df.withColumn("a",fudf(df.id)).show() However, the implementation of the function I need is in java and not in python. I need to wrap it somehow so I can call it in a similar way from python. My

Py4J has bigger overhead than Jython and JPype

由 泪湿孤枕 提交于 2019-12-07 05:30:17
问题 After searching for an option to run Java code from Django application(python), I found out that Py4J is the best option for me. I tried Jython, JPype and Python subprocess and each of them have certain limitations: Jython. My app runs in python. JPype is buggy. You can start JVM just once after that it fails to start again. Python subprocess. Cannot pass Java object between Python and Java, because of regular console call. On Py4J web site is written: In terms of performance, Py4J has a

How to call java from python using PY4J

由 丶灬走出姿态 提交于 2019-12-06 05:20:54
问题 I want to call java from python with Py4J library, from py4j.java_gateway import JavaGateway gateway = JavaGateway() # connect to the JVM gateway.jvm.java.lang.System.out.println('Hello World!') I've got the following error: "Py4JNetworkError: An error occurred while trying to connect to the Java server". It's seems that no JVM is running, how to fix that? 回答1: package test.test; import py4j.GatewayServer; public class AdditionApplication { public int addition(int first, int second) { return

Using py4j to send matrices to from Python to Java as int[][] arrays

由 孤街醉人 提交于 2019-12-04 18:05:20
I've been using py4j to build a user-friendly Python library around a less user-friendly Java library. For the most part, this has been a breeze, and py4j has been a great tool. However, I've come across a snag when sending matrices between Python and Java. Specifically, I have a static function in java that accepts, as its arguments, an integer matrix: public class MyClass { // ... public static MyObject create(int[][] matrix) { // ... } } I'd like to be able to call this from Py4j like so: def create_java_object(numpy_matrix): # <code here checks that numpy_matrix is a (3 x n) integer matrix
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